docs: Phase A repo structure — archive, product, kebab-case

- Move copilot history and CSV to docs/archive/
- Add docs/product/ (SSP, intermediate, genre packs) and engineering/adrs/
- Rename all spaced/special-char doc paths to kebab-case
- Nest competitive GTM under docs/gtm/competitive/
- Point README and NORTH_STAR at CANONICAL_STRATEGY
- Leave code/ unchanged for later monorepo Phase B

docs/README.md

@@ -0,0 +1,13 @@
+# Documentation
+
+| Folder | Role |
+|--------|------|
+| [strategy/](./strategy/) | **Operating truth** — start with CANONICAL_STRATEGY.md |
+| [product/](./product/) | SSP, intermediate, genre packs |
+| [gtm/](./gtm/) | Channels, sales, competitive |
+| [investors/](./investors/) | Market and financial packaging |
+| [engineering/](./engineering/) | Roadmap and ADRs |
+| [legal/](./legal/) | Privacy, IP, partnership skeletons |
+| [archive/](./archive/) | Historical only — not operating docs |
+
+Governance: if two docs disagree, resolve against strategy or deliberately change strategy.