Enhance dashboard with .factory/ artifact browser

[abhi1092]

Factory experiment 3. Hypothesis: Enhance dashboard to browse .factory/ contents.

What to Build

Add .factory/ artifact browsing to the existing web dashboard in three parts:

1. Two new FastAPI endpoints in factory/dashboard/app.py

• GET /api/projects/{name}/factory/browse?path=strategy — lists files in a .factory/ subdirectory (strategy, reviews, experiments, archive). Returns file names, sizes, and last-modified timestamps. Directory traversal guarded by allowlisting subdirectories.
• GET /api/projects/{name}/factory/file?path=strategy/current.md — returns raw file content for rendering. Path restricted to .factory/ subtree with traversal checks.

2. Frontend artifact browser in factory/dashboard/static/index.html

• Sidebar navigation with sections: Strategy (current.md, research.md, observations.md, backlog.md), Reviews (ceo-verdict-*.md, *-latest.md), Experiments (per-experiment artifacts), Archive (research notes, patterns, sources), Backlog
• Clicking a file opens a slide-out panel with markdown rendered to HTML (use marked.js via CDN)
• Collapsible tree structure for experiments/ and archive/ subdirectories
• JSON files rendered with syntax highlighting using a

   block

3. Tests in tests/test_dashboard.py

• Test both new endpoints with fixture .factory/ directories
• Test path traversal rejection (e.g., ../../etc/passwd)
• Test missing file returns 404

Acceptance Criteria

• Both browse and file endpoints work correctly
• Path traversal is properly guarded
• Frontend renders markdown files and JSON files
• Sidebar navigation with all sections
• All existing dashboard tests pass
• Eval score does not regress

Constraints

• Read CLAUDE.md before starting
• Do NOT touch files outside declared scope
• Do NOT modify eval/score.py or .factory/
• Use vanilla JS — no React/Vue frameworks
• Keep existing dashboard completely intact