Bootstrap agent-ready docs and permissions (D-036)

Root AGENTS.md is now the single source of truth for coding agents;
CLAUDE.md, GEMINI.md and docs/CLAUDE.md are pointers. The product spec
moves from docs/CLAUDE.md to PRODUCT.md, DESIGN.md records the shipped
visual system, and docs/PERMISSIONS.md defines agent permission tiers
rendered to .claude/, .codex/ and .gemini/. Adds docs/specs/ and
docs/plans/, logs issues noticed (not fixed) in WorkBreakdown.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -38,3 +38,8 @@ __pycache__/
 
 # Finder (MacOS) folder config
 .DS_Store
+
+# agent-local files (D-036)
+CLAUDE.local.md
+.claude/settings.local.json
+.claude/worktrees/