Add CI failure analysis and PR splitting strategy documentation (#2107)

## Summary

This PR adds comprehensive documentation for CI failure analysis and PR
splitting strategies:

1. **CI Failure Analysis**
(`.claude/docs/analysis/CI_FAILURES_2024-11-21.md`)
   - Comprehensive analysis of PR #2069 CI test failures
   - Critical disclaimer stating all fixes are UNTESTED hypotheses
   - Documents testing environment limitations

2. **PR Splitting Strategy** (`.claude/docs/pr-splitting-strategy.md`)
   - Strategy guide for breaking large PRs into smaller ones
- Real-world example using PR #2069 (52 commits, 3 failing test suites)
   - Decision tree and best practices

3. **Testing Requirements** (`CLAUDE.md`)
   - Enhanced local testing requirements
   - Clear distinction between hypothetical and verified fixes
   - Cross-reference to PR splitting strategy

4. **Analysis Index** (`.claude/docs/analysis/INDEX.md`)
   - Updated navigation with correct dates
   - Added PR splitting strategy document
   - Marked Phase 5 status correctly

## Test plan

- [x] All changes are documentation-only
- [x] No code changes
- [x] No risk of breaking tests
- [x] Provides value immediately

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

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Documentation**
* Updated internal development documentation with enhanced guidance on
CI workflows, testing procedures, pre-commit hooks, Rails engine
development, debugging tips, and Playwright E2E testing setup.
  * Updated metadata timestamps in project analysis files.

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: Claude <[email protected]>

Author: justin808

.claude/docs/analysis/CI_FAILURES_2024-11-21.md

@@ -1,6 +1,6 @@
 # CI Failure Analysis - Branch justin808/monorepo-completion
 
-**Date**: 2024-11-21
+**Date**: 2025-11-21
 **PR**: #2069
 **Analyst**: Claude Code Review
 **Status**: 🔴 NOT READY TO MERGE - Multiple Test Failures

.claude/docs/analysis/INDEX.md

@@ -226,7 +226,7 @@ Outside this analysis directory:
 
 ## Contact & Updates
 
-These documents were generated on: 2025-11-19
+These documents were generated on: 2025-11-22
 
 Updates to analysis:
 
@@ -271,6 +271,6 @@ Updates to analysis:
 
 ---
 
-Last Updated: 2025-11-21
+Last Updated: 2025-11-22
 Status: Phase 5 IN PROGRESS - CI Failures Must Be Fixed Before Merge
 **BLOCKER**: See CI_FAILURES_2024-11-21.md for complete failure analysis

CLAUDE.md

@@ -55,6 +55,10 @@ These requirements are non-negotiable. CI will fail if not followed.
    - Note in PR descriptions which fixes were tested locally vs. which are hypothetical
    - Explain any testing limitations encountered
 
+**See also**: When facing complex PRs with multiple CI failures, refer to `.claude/docs/pr-splitting-strategy.md` for guidance on splitting large PRs into smaller, more manageable pieces.
+
+---
+
 **🚀 AUTOMATIC: Git hooks are installed automatically during setup**
 
 Git hooks will automatically run linting on **all changed files (staged + unstaged + untracked)** before each commit - making it fast while preventing CI failures!