docs: add repo-local project memory under .claude/memory/

Versioned, per-topic project memory (index + entries): IIOS overview, the generic-safety
rule, run/test + the replay.spec flake workaround, recent features (Supabase auth,
reactions/pins/saves, mentions, media, notifications), the chat-web consumer, and workflow
conventions. CLAUDE.md points to it as the accumulating-notes companion to the canonical rules.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/memory/feedback_generic_safety.md

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+---
+name: feedback_generic_safety
+description: THE #1 locked rule — the kernel must never hardcode chat/domain vocabulary
+metadata:
+  type: feedback
+---
+
+**The kernel must stay generic.** No `'dm'` / `'group'` / `'reaction'` / `'emoji'` / `'mention'`
+literals in kernel or messaging *logic*. If a reviewer asked "is this a chat backend now?" the
+answer must stay **no**.
+
+**Why:** IIOS is a generic interaction OS; chat is one consumer. Baking chat meaning into the
+kernel destroys reuse (support/community/meetings share the same core).
+
+**How to apply:** domain meaning lives in exactly three places, never the kernel —
+1. **OPA policy** (`DevOpaPort` → real OPA): DM-cap, group-admin, governed-join, media limits,
+   notification triggers.
+2. **Opaque attributes** the kernel stores but never interprets: `thread.metadata.membership`
+   (`dm`/`group`), interaction annotations (opaque `annotationType`+`value` → app writes
+   `reaction`/`pin`/`save`), `mentions[]` (opaque userId notify-list; kernel never parses `@`).
+3. **The app** (chat-web): rendering + product semantics.
+
+Reading an opaque attr inside a **policy/notification gate** (`membership === 'dm'` in
+`DevOpaPort` or `notification.projector.ts`) is OK — that file IS the policy plane. Everywhere
+else, keep generic. Verify before committing:
+`grep -rniE "'dm'|'group'|reaction|emoji" packages/iios-service/src | grep -v spec` — hits only
+in policy/notification/app-facing layers or comments. Also run `pnpm boundary`.
+Related: [[project_iios_overview]].