Add the coordination repository coordination: CLAUDE.md, manga-org skill, SessionStart hook

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

CLAUDE.md

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+# Manga Circus — instructions for agents
+
+Self-hosted manga/comic/webtoon reader. Read `README.md` and `docs/architecture.md`, `docs/library-format.md`, `docs/scraper-guide.md` before changing anything.
+
+## Rules
+- **Principles (architecture §1):** zero npm dependencies, no framework, no build step, one process and one data file, the file system is the source of truth, the app never writes to the library.
+- **UI:** build DOM only with `h()` (no `innerHTML`), relative URLs only, `mc.`-prefixed localStorage keys, `http(s)` links only.
+- **Senpai integration** is on branch `senpai-integration` (`/api/senpai/*` proxy, "Who's here" side sheet), optional and invisible without `SENPAI_URL`. It must never show anything beyond the reader's horizon (spoiler rules live in Senpai, `docs/decisions.md`).