restructure: AGENTS.md canonical + docs/guides with .claude/rules symlinks

Rename CLAUDE.md -> AGENTS.md (cross-vendor standard) with a relative
CLAUDE.md symlink so Claude Code still loads it. Move each .claude/rules
file into docs/guides/ (paths: frontmatter preserved) and replace the
rules file with a relative symlink into the guide. Repoint the AGENTS.md
index paragraph at docs/guides/ so non-Claude agents find the guides.

docs/guides/redaction.md

@@ -0,0 +1,23 @@
+---
+paths:
+  - "image/app/redaction/**"
+  - "image/app/redaction_gateway.py"
+  - "docs/REDACTION_GATEWAY.md"
+---
+
+# Redaction (`/scrub` + `/rehydrate`)
+
+- `image/app/redaction/scrub.py` + `test_scrub_leak.py` are vendored **byte-for-byte** from the CRM repo (sha recorded in `redaction/__init__.py`). **Never edit them here** — change them in the CRM repo, re-vendor (`cp`), update the sha, re-run the leak test.
+- The gateway around the vendored scrubber is `image/app/redaction_gateway.py`. Its token-map store lives on `/data` (`REDACTION_MAP_DB`, default `/data/redaction_maps.db`) and fails closed if it can't open — set the env var when running outside the container.
+
+## Test suites — both must pass before shipping ANY redaction change
+
+```bash
+cd image
+.venv/bin/python -m app.redaction.test_gateway        # /scrub + /rehydrate acceptance; offline, no cluster needed
+.venv/bin/python app/redaction/test_scrub_leak.py     # vendored golden-file leak test; offline
+```
+
+Keep the leak test green against the vendored `scrub.py` after any re-vendor.
+
+Policy context: scrubbed text via `/scrub` is the **only** sanctioned path toward frontier/cloud models — see the whole-repo privacy rule in CLAUDE.md.