feat: add export_report tool, expand tilde path, and support ai error retry resilience

[zx06]

Summary

1. AI Tool Resilience & Auto-Retry: Retain strict JSON schema validation, inject error feedback to context when tool arguments parsing fails, and auto-retry up to 2 times without manual intervention.
2. Path Tilde Expansion: Expand ~ and ~/ in export file paths to the user's home directory.
3. Export Tools Separation:
   • export_data: dedicated to dumping raw cached datasets, restricted to csv and json.
   • export_report: new tool dedicated to saving comprehensive Markdown analysis reports with human-in-the-loop confirmation.
4. Docs & Tests: Updated RFC 0013 revision history, docs/ai.md, and added comprehensive unit and e2e tests.

[codecov]

Codecov Report

❌ Patch coverage is 82.32759% with 41 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.78%. Comparing base (22fa6f7) to head (58cf86d).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
internal/export/exporter.go	64.81%	13 Missing and 6 partials ⚠️
internal/tui/model.go	85.45%	12 Missing and 4 partials ⚠️
internal/tui/render.go	68.42%	5 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #73      +/-   ##
==========================================
+ Coverage   82.21%   82.78%   +0.57%     
==========================================
  Files          62       62              
  Lines        5983     6147     +164     
==========================================
+ Hits         4919     5089     +170     
+ Misses        798      791       -7     
- Partials      266      267       +1     

Flag	Coverage Δ
e2e	28.39% <17.67%> (-0.26%)	⬇️
integration	28.39% <17.67%> (-0.26%)	⬇️
unittests	75.41% <80.17%> (+0.69%)	⬆️

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
3.0% Duplication on New Code

See analysis details on SonarQube Cloud