fix(ci): make PR-template inline-description contract explicit (#10558)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - Contributors use the PR template to describe changes before review
> - The linked-issue gate reads literal template labels, not freeform
prose
> - The template did not state that rule, so a good prose summary could
fail on first submission
> - The gate also skipped two issue template paths that the PR template
already points to
> - This pull request makes the template and the gate match the same
contract
> - The benefit is that a good-faith author can pass the check on the
first try

## Linked Issues or Issue Description

No public issue exists.

Related public PR: #7762.

The problem is a mismatch between the PR template and the linked-issue
gate.
The template gave a bare placeholder and did not explain the
literal-label rule.
The gate also missed the enhancement and docs issue templates.

## What Changed

- Replaced the bare PR-template placeholder with labeled inline
skeletons for bug, feature, and adapter paths.
- Added one sentence that says the gate reads literal labels on separate
lines.
- Added the enhancement and docs issue template field sets to the
linked-issue gate.
- Added and updated tests for prose-only bodies, template skeleton
bodies, and extra issue template coverage.

## Verification

- `node --test .github/scripts/tests/check-pr-linked-issue.test.mjs`
- The branch contains one commit:
`561f1ed3a1434ed4562306f74d40968163ef1444`

## Risks

Low risk.
The three-field minimum stays in place.
The main change is clearer author guidance in the PR template.

## Model Used

OpenAI Codex, GPT-5, tool use.

## 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 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
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

.github/PULL_REQUEST_TEMPLATE.md

@@ -19,10 +19,11 @@
 ## Linked Issues or Issue Description
 
 <!--
-  Required. Pick ONE of the following two paths:
+  Required. Pick ONE of the two paths below.
 
-  (A) Issue exists — tag each linked issue with `Fixes: #123`, `Closes #123`,
-      or `Refs #123`. Include duplicates and closely related issues too.
+  (A) Issue exists — replace the placeholder below with your issue links.
+      Tag each linked issue with `Fixes: #123`, `Closes #123`, or `Refs #123`.
+      Include duplicates and closely related issues too.
 
   Only reference PUBLIC GitHub issues/PRs here. Do NOT paste internal,
   instance-local Paperclip references — ticket ids like PAPA-123 / PAP-224,
@@ -30,11 +31,18 @@
   contributors cannot open them. See CONTRIBUTING.md → "No Internal Issue
   References".
 
-  (B) No issue exists — describe the underlying problem here, following the
-      relevant issue template so reviewers get the same fields:
-        • Bug:     .github/ISSUE_TEMPLATE/bug_report.yml
-        • Feature: .github/ISSUE_TEMPLATE/feature_request.yml
-        • Adapter: .github/ISSUE_TEMPLATE/adapter_request.yml
+  (B) No issue exists — describe the underlying problem here. Follow the issue
+      template that fits your change. Open the matching file and copy its field
+      labels into your description:
+        • Bug:         .github/ISSUE_TEMPLATE/bug_report.yml
+        • Feature:     .github/ISSUE_TEMPLATE/feature_request.yml
+        • Adapter:     .github/ISSUE_TEMPLATE/adapter_request.yml
+        • Enhancement: .github/ISSUE_TEMPLATE/enhancement.yml
+        • Docs:        .github/ISSUE_TEMPLATE/docs_issue.yml
+      An automated check reads the literal bold labels AND the content under
+      each label. Keep at least three of these labels, each alone on its own
+      line, and write real content under each. A label with only the bare "-"
+      placeholder does not count, and the check fails.
 
   See CONTRIBUTING.md → "Link Issues or Describe Them In-PR".
 -->