feat(pr-watch): integrate reviews/comments into pr-watch

The pr-watch skill and script now cover reviews/comments, not just CI checks.
An agent reading only the pr-watch skill now knows to track both.

.agents/skills/pr-watch/SKILL.md:
- Reframed: 'watching a PR' means checks AND reviews
- Added 'Reviews and Comments' section with the three surfaces table
- Added 'Review Obligations' subsection (answer feedback, identity line, etc.)
- Documented --reviews (default) and --no-reviews flags
- Cross-references AGENTS.md for full workflow details

scripts/pr-watch:
- Added --reviews (default) and --no-reviews flags
- After exit 0 (green/mergeable), calls scripts/pr-reviews to show all
  reviews and comments. Does not change exit code — answering is agent's job.
- Updated usage text to document the new behavior
- Composes with existing pr-reviews (fixture mode passes through)

scripts/pr-watch-test.sh:
- Added mk_reviews_empty() and mk_reviews_with_review() helpers
- Added review fixtures to all cases that exit 0 (pr-reviews needs them)
- Added tests: 'green with reviews shows review output' and
  '--no-reviews skips review output'
- All 56 tests pass

AGENTS.md / context/cloud-agents.md:
- Updated cross-references to point to pr-watch skill as agent-facing recipe
- Simplified text now that pr-watch handles reviews automatically

Co-authored-by: Ed Langley <fiddlerwoaroof@users.noreply.github.com>

context/cloud-agents.md

@@ -170,12 +170,12 @@ environment, where egress leaves through your own network boundary.
 
 For any PR you own, **track both CI checks and GitHub comments/reviews**:
 
-- **CI checks**: Use the `pr-watch` skill or `scripts/pr-watch`.
-- **Reviews and comments**: Use `./scripts/pr-reviews <n>` — reviews are a separate API
-  surface from comments, and Codex/ChatGPT reviews arrive as *reviews* not comments.
+- **`scripts/pr-watch <n>`**: Waits for checks, then prints all reviews/comments (default).
+  Reviews are a separate API surface — Codex/ChatGPT reviews arrive as *reviews* not comments.
 - **Answer feedback** with an identity line naming the model before marking work done.
 - **Re-check after push** that reviews target the current head SHA.
 
+The `pr-watch` skill (`.agents/skills/pr-watch/SKILL.md`) is the agent-facing recipe.
 See AGENTS.md "PR Tracking: Checks AND Reviews" and "Shipping a wave" for the full workflow.
 
 ---