feat(ui): turn Artifacts V1 on for every instance and hide its toggle (#19164)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - Artifacts show the output of agent work on the Artifacts page, in
the panel Artifacts tab, and in the task thread
> - #17228 added the Artifacts V1 presentation behind an experimental
setting that is off by default
> - The presentation is now ready for all users, so an opt-in toggle is
no longer necessary
> - A new default alone does not reach all instances, because each
experimental write persists every flag
> - This pull request removes the toggle and turns V1 on for every
instance
> - The benefit is one artifact presentation for all users, with an off
switch for hosting operators

## Linked Issues or Issue Description

Refs #17228
Refs #17263

**Is your feature request related to a problem? Please describe.**
Artifacts V1 shows only on instances where an admin turned on an
experimental setting. Other users see the previous cards.

**Describe the solution you would like**
Show Artifacts V1 on all instances. Remove the toggle from Experimental
settings.

**Describe alternatives you have considered**
A new default without a change to the hook. This does not work, because
many instances have a stored false that nobody chose, and no toggle
would remain to change it.

## What Changed

- Removed the Artifacts V1 card from Instance Settings, Experimental.
- Changed `enableArtifactsV1` to default on in the schema, the feature
catalog, and the settings service.
- Changed `resolveArtifactsV1Enabled` to ignore a stored false. It
honours false only when the value comes from managed config.
- Kept the flag and the previous cards, so a hosting operator can hold
V1 off.
- Kept the key in the Cloud staging list, so a managed false does not
hold V1 off on staging.
- Updated unit tests, the Artifacts V1 plan, and the directions-lab
Today reference.
- Moved the attachment and upload e2e specs and the runner download
helper to the V1 rows.
- Added V1 tests for a Markdown review: expansion, deep link, and open,
raw and download actions.

## Verification

- `cd ui && npx vitest run`: one test file failed before its fix. That
file tests the previous cards, and it now mocks the hook to off. I reran
it with the other changed UI tests, and they pass. I did not repeat the
full UI run after the fix.
- `npx playwright test --config tests/e2e/playwright.config.ts
tests/e2e/text-attachment-tabs.spec.ts
tests/e2e/artifact-uploads.spec.ts
tests/e2e/artifact-tab-arrival.spec.ts`: 10 tests pass on V1.
- `tests/e2e/cloud-auth.spec.ts` failed once in CI on a task heading. It
does not touch artifacts, and 10 local runs pass.
- `cd server && npx vitest run src/__tests__/instance-settings`: 183
tests pass.
- `cd packages/shared && npx vitest run src/feature-catalog.test.ts
src/validators/instance.test.ts`: 35 tests pass.
- `pnpm run check:token-gates` and the `ui` and `server` typechecks
pass. I did not run the full repository check.
- In the artifact directions lab, with no stored settings, the Today
right panel renders the V1 rows.
- I did not test this on a live instance. After merge, confirm on
staging that the Experimental page has no Artifacts V1 card and that all
three surfaces show V1.

## Risks

- All users see V1 after the next release, not only staging users. To
revert, revert this pull request.
- Users cannot turn V1 off. Only a hosting operator can, through managed
config, and not on Cloud staging.
- An instance with a managed `enableArtifactsV1: false` stays on the
previous cards. The cloud harness source has no reference to this key,
but I cannot read the live fleet configuration.
- V1 surfaces render before settings load. An operator-held instance can
briefly show V1 before the previous cards.
- Admins who use the API can still write the flag. The write has no
effect on unmanaged instances.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- Anthropic Claude Opus 5.5 (`claude-opus-5-5`) in Claude Code, with
tool use and code execution.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [ ] All Paperclip CI gates are green
- [ ] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/directions-lab/references/today-fixtures-and-build.md

@@ -45,7 +45,7 @@ export function loadKit(id: DirectionId): Promise<DirectionKit> {
 - `ThreadWorkProduct`: a task document becomes a `TaskChatProtocolCard` resource item with ``subtitle: `Document · rev ${artifact.revision}` ``; anything else becomes `RichWorkProductCard` with `workProductHref(workProduct)` (`ThreadWorkProduct.tsx:13-31`; the product split is `ui/src/components/TaskChatThread.tsx:1290-1312`).
 - `ThreadAttachments`: mirrored; uses `@/components/ui/attachment`, `ArtifactPreview`, `fileKindForAttachment`, `formatFileSize`, `isImageAttachment`, `isVideoLikeOutput` (`ThreadAttachments.tsx:1-15`).
 
-**GENERIC**, flag-gated components. Before mounting, grep the feature's flag hook under `ui/src/components` and `ui/src/pages`. For artifacts, `useArtifactsV1Enabled()` is called at `IssuePropertiesArtifactsTab.tsx:414`, `TaskChatBubble.tsx:149`, `TaskChatProtocolCard.tsx:1045` and in `pages/Artifacts.tsx`; it resolves `settings?.enableArtifactsV1 === true` (`ui/src/hooks/useArtifactsV1Enabled.ts:7-9`) from `GET /api/instance/settings/experimental` (`ui/src/api/instanceSettings.ts:20-21`). The artifact stub has no route for it, answers `{}`, and the flag is false: Today's panel and its task-document thread row render the flag-OFF presentation (the generic card from `TaskChatProtocolCard.tsx:1072`), while `ArtifactCard`, `ArtifactGroupCard` and `RichWorkProductCard` are flag-independent. To show a flagged presentation under Today, register a route returning `{ enableArtifactsV1: true }` for that pathname. A generated lab already has that route: `api-routes.ts` answers any pathname ending `/instance/settings/experimental` with `registry.today.flags` (`{}` as scaffolded), so set the flag in `registry.ts` (`today: { flags: { enableArtifactsV1: true } }`) or at run time with `setLabFlags`.
+**GENERIC**, flag-gated components. Before mounting, grep the feature's flag hook under `ui/src/components` and `ui/src/pages`. For artifacts, `useArtifactsV1Enabled()` is called at `IssuePropertiesArtifactsTab.tsx:414`, `TaskChatBubble.tsx:149`, `TaskChatProtocolCard.tsx:1045` and in `pages/Artifacts.tsx`; it resolves to on unless a managed `enableArtifactsV1: false` holds it off (`resolveArtifactsV1Enabled` in `ui/src/hooks/useArtifactsV1Enabled.ts`), read from `GET /api/instance/settings/experimental` (`ui/src/api/instanceSettings.ts:20-21`). The artifact stub has no route for it and answers `{}`, so Today's panel and its task-document thread row render the V1 rows, while `ArtifactCard`, `ArtifactGroupCard` and `RichWorkProductCard` are flag-independent. To show the previous cards under Today, return `{ enableArtifactsV1: false, managedKeys: { enableArtifactsV1: { managed: true, managedBy: "paperclip-cloud" } } }` for that pathname. A generated lab already has that route: `api-routes.ts` answers any pathname ending `/instance/settings/experimental` with `registry.today.flags` (`{}` as scaffolded), so set those values in `registry.ts` or at run time with `setLabFlags`.
 
 ## 2. Adapters: lab fixtures to product types