fix(mcp): eliminate "No such tool available" race at agent wakeup

When Paperclip wakes the CEO and the model issues an mcp__legal-ai__*
call within ~10s of session init, Claude Code sometimes returns
"No such tool available" because the legal-ai MCP server hasn't
finished bringing up its tool catalog yet. Observed twice today on
CMPA precedent-extraction wakeups (sessions 9989fbaf and a9c61801);
the agent fell back to bash + .venv/bin/python and finished the work,
but the race needed fixing on the server side.

Three changes that close the window:

1. Lazy schema init (services/db.py + server.py)
   `init_schema()` was awaited inside the FastMCP lifespan, blocking
   the `initialize`/`tools/list` handshake until ~10 CREATE TABLE IF
   NOT EXISTS statements ran. Under contention (two CEOs waking at
   once for different companies) this stretched. Now the lifespan
   returns immediately and `get_pool()` runs the schema migrations
   exactly once on first DB access, guarded by an asyncio.Lock.
   tools/list is answered in milliseconds regardless of DB state.

2. Lazy heavy imports
   - services/embeddings.py: voyageai (~450ms) loaded only inside
     _get_client()
   - services/extractor.py: google.cloud.vision (~550ms) loaded only
     inside _get_vision_client() and _ocr_with_google_vision()
   These two were being imported at module top from
   legal_mcp.tools.documents -> services.processor -> services.{
   extractor,embeddings}, so the FastMCP server couldn't even start
   responding until both finished. Cold start dropped from 2.7s to
   1.17s end-to-end (init + tools/list response).

3. Agent-side warmup + retry guidance (.claude/agents/legal-ceo.md)
   Even with a fast server, the model can still race on the very
   first call. The precedent-extraction section now tells the CEO
   to call workflow_status as a warmup probe and to retry after a
   short sleep if it sees "No such tool available", before falling
   back to the python bypass.

Also expanded the precedent-tool whitelists on the sub-agents that
delegate halacha/library work (commits 4a9a6b7 + 7ee90dc added the
tools to the MCP server but only the CEO got them in its allowed
list). Added to: legal-researcher (full extraction set), legal-analyst
(library_get/list + halacha review), legal-writer (library lookups +
halacha_review), legal-qa (library_get + halacha_review), and the two
that the CEO was already missing (halacha_review, halachot_pending).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/agents/legal-writer.md

@@ -20,6 +20,9 @@ tools:
   - mcp__legal-ai__write_block
   - mcp__legal-ai__search_decisions
   - mcp__legal-ai__search_precedent_library
+  - mcp__legal-ai__precedent_library_get
+  - mcp__legal-ai__precedent_library_list
+  - mcp__legal-ai__halacha_review
   - mcp__legal-ai__search_case_documents
   - mcp__legal-ai__get_style_guide
   - mcp__legal-ai__workflow_status