rename(547): the plugin is grimoire — manifest, MCP key, hooks, env, skills

Step 3 of the Scribe -> Grimoire rename.

- Plugin `grimoire` in marketplace `grimoire-plugin`, MCP server key
  `grimoire`, so tools reach a session as mcp__plugin_grimoire_grimoire__*.
- hooks/scribe_* -> hooks/grimoire_*, their shell functions and the TMPDIR
  ledgers with them; SCRIBE_URL / SCRIBE_TOKEN / SCRIBE_HOOK_DIR /
  SCRIBE_LEDGER_DIRS -> GRIMOIRE_*; the project marker is `.grimoire`.
- skills/using-scribe -> using-grimoire, /grimoire:sync, stored processes
  arrive as grimoire-proc-<slug>; moment_actions names them the same way.
- Migration 0124 rewrites stored skill names (rule_moments,
  rule_moment_judgments, moment_mappings) from scribe:/scribe-proc- to
  grimoire:/grimoire-proc-, so a rule mounted on a skill keeps firing.
- Settings' install commands and MCP-only defaults, the docs and the
  tests follow.
- scripts/check_plugin.py drops the smoke event for a report-check hook
  that has no file in plugin/hooks.

Kept on purpose: the secret-sealing label, and the names that let backups
written as Scribe restore and be counted.

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

tests/test_precompact_hook.py

@@ -38,7 +38,7 @@ from pathlib import Path
 import pytest
 
 ROOT = Path(__file__).resolve().parents[1]
-HOOK = ROOT / "plugin" / "hooks" / "scribe_precompact_preserve.sh"
+HOOK = ROOT / "plugin" / "hooks" / "grimoire_precompact_preserve.sh"
 HOOKS_JSON = ROOT / "plugin" / "hooks" / "hooks.json"
 
 EVENT = {"session_id": "s1", "transcript_path": "/tmp/t.jsonl", "cwd": "/repo",
@@ -50,7 +50,7 @@ def _run(event: dict, tmpdir: str | None = None) -> subprocess.CompletedProcess:
     """Run the hook with its ledger directory ISOLATED.
 
     The hook reads this session's rule ledgers, and they live under
-    `$TMPDIR/scribe-priorart`. Without an override these tests would read the
+    `$TMPDIR/grimoire-priorart`. Without an override these tests would read the
     machine's real /tmp: on a developer box mid-session that is not empty, and
     the output would depend on what some other session happened to leave
     behind. None of the assertions below would fail on it today, which is