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>

README.md

@@ -8,8 +8,11 @@ users can optionally run inference on the **server** instead, backed by
 [faster-whisper](https://github.com/SYSTRAN/faster-whisper) (CTranslate2)
 through a small Python sidecar (`server-py/`, Decisions.md D-013).
 
-See `Architecture.md` for the design, `Decisions.md` for the decision log, and
-`CLAUDE.md` for the toolchain rules (Bun everywhere — no npm/node).
+See `docs/Architecture.md` for the design, `docs/Decisions.md` for the decision
+log, and `PRODUCT.md` for the product spec.
+
+**AI coding agents:** read [`AGENTS.md`](AGENTS.md) — the single source of truth
+for commands, conventions and boundaries (Bun everywhere — no npm/node).
 
 ## Development