feat(runner): add remote execution substrate (#12638)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work.
> - Paperclip Runner gives native runs a durable and governed execution
path.
> - The current native path runs on the control-plane host.
> - Remote environments need an authenticated execution-target contract.
> - The contract must not change direct adapters or enable new runtimes
by default.
> - This pull request adds the remote execution substrate and Daytona
ingress.
> - The benefit is a bounded base for later remote runner transport
work.

## Linked Issues or Issue Description

Refs #12616.
Refs #12352.

**Subsystem affected**

Cross-cutting. This change touches runner transport, server
orchestration, plugin contracts, and shared settings.

**Problem or motivation**

Native execution cannot resolve an authenticated runner ingress through
a remote environment. The server also lacks one provider-neutral
contract for remote execution targets.

**Proposed solution**

Add a default-off runner preview ingress capability. Add
transport-neutral runner connectivity. Add remote execution target and
lifecycle handling. Add a Daytona ingress implementation with redacted
credentials.

**Alternatives considered**

A provider-specific server path would duplicate orchestration and
authorization. A public endpoint without an environment contract would
weaken the trust boundary.

**Roadmap alignment**

This work supports the Cloud and Sandbox agents milestone. It also
supports self-healing runs and governed tool access.

## What Changed

- Added execution-target traits for local, SSH, and sandbox
environments.
- Added plugin RPC contracts for runner ingress endpoints.
- Added authenticated Daytona preview ingress.
- Added transport-neutral PRP outbound connections.
- Added remote runner artifact verification and fail-closed provider
selection.
- Added bounded native session resume, cancellation, and lifecycle
recovery.
- Preserved Codex-only selection for fresh experimental runner starts.
- Preserved all direct adapter execution and finalization paths.
- Removed stale Pi provider-pack requirements that security review
rejected.
- Kept the rollout controls off by default.
- Did not change pnpm-lock.yaml, Cargo, database migrations, or GitHub
workflows.

## Verification

- GitHub Actions will run the repository test, typecheck, build,
security, and policy gates.
- Focused tests cover ingress validation, redaction, execution targets,
remote lifecycle, cancellation, resume, and legacy adapter selection.
- Local tests were not run. The requested verification policy uses
GitHub Actions for this series.
- `git diff --check origin/master...HEAD` passes.
- The diff contains 52 files.

## Risks

- Remote execution crosses a trust boundary.
- The implementation validates target capabilities, artifact digests,
provider-pack pins, and connection metadata.
- The feature remains default-off.
- Fresh native selection remains Codex-only.
- Existing direct adapters remain on the legacy path.
- This PR does not yet make remote Codex runnable. The next PR adds the
Rust WSS and TLS transport.

## Model Used

OpenAI Codex with GPT-5.6. The work used high-reasoning agent mode,
repository tools, GitHub tools, and parallel code-audit agents.

## 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 or instance-local Paperclip issues
or links
- [x] My branch name describes the change and contains no internal
Paperclip ticket id
- [ ] 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 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

server/src/services/native-runtime/runtime-mode.ts

@@ -40,7 +40,7 @@ export type NativeRuntimeResolution =
       reason: "eligible_opt_in";
       profile: {
         mode: "native";
-        backend: "codex_app_server";
+        backend: "codex_app_server" | "opencode_server" | "acpx_runtime";
         protocolVersion: 1;
       };
       authorityDecision: NativeStatusDecision;
@@ -129,12 +129,6 @@ export function resolveNativeRuntimeMode(input: {
       "Paperclip Runner requires a standard, planning, or ask task.",
     );
   }
-  if (!input.target || input.target.kind !== "local") {
-    throw ineligible(
-      "paperclip_runner_environment_unsupported",
-      "Paperclip Runner currently requires a local execution environment.",
-    );
-  }
   const rollout = resolveNativeMigrationStatus({
     facts: { applicationEnabled: true },
     priorIssueStatus: "in_progress",
@@ -267,13 +261,17 @@ export function resolveHeartbeatNativeRuntimeMode(input: {
         );
       }
       const driverKind = input.persisted.driverKind;
-      const backend = driverKind === null
-        || driverKind === undefined
-        || driverKind === "codex"
-        || driverKind === "codex_app_server"
-        ? "codex_app_server"
-        : null;
-      if (!backend) {
+      const backend = driverKind === "opencode_server"
+        ? "opencode_server"
+        : driverKind === "acpx_runtime"
+          ? "acpx_runtime"
+          : driverKind === null
+              || driverKind === undefined
+              || driverKind === "codex"
+              || driverKind === "codex_app_server"
+            ? "codex_app_server"
+            : null;
+      if (backend === null) {
         throw ineligible(
           "paperclip_runner_driver_unsupported",
           `Persisted Paperclip Runner driver is unsupported: ${driverKind}`,