fix(tz): timezone-aware datetimes — unblock TZ=Asia/Jerusalem (#210)

Backend follow-up to INV-UI9 (X6 §"אודיט-נלווה"): make server-side
datetimes explicit so flipping the container to TZ=Asia/Jerusalem cannot
silently skew stored or displayed timestamps. Storage stays UTC; human
display is Israel time.

- audit.py: naive datetime.utcnow() → datetime.now(timezone.utc) for the
  TIMESTAMPTZ audit_log.created_at. Under TZ=Asia/Jerusalem the naive UTC
  wall-clock would be read as Israel-local and stored ~3h off. (§6: no
  silent skew.)
- calibrate_effort.py: _ts() report stamp now Israel-time via
  ZoneInfo("Asia/Jerusalem") with a filename-safe "-IL" suffix (script runs
  on the UTC host); added a labeled "שעון ישראל" line to the report header
  so the chair-facing timestamp is unambiguous. --self-test still ALL PASS.
- research_md.py: display fields made deterministic Israel-tz —
  update_chair_position timestamp (datetime.now(IL_TZ)) and parse() mtime
  (datetime.fromtimestamp(..., tz=IL_TZ)) — correct regardless of process TZ.

Left intentionally Israel-local-day date.today()/year-cutoff call sites
untouched (drafting/party_claims_summary/block_writer/court_fetch_supreme)
— a Jerusalem committee wants the Israel calendar day; they resolve
correctly once TZ flips.

Invariants: INV-UI9 (store-UTC / display-Israel, server side); §6
(timezone-aware datetimes, no silent ~3h skew).

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

mcp-server/src/legal_mcp/services/audit.py

@@ -7,7 +7,7 @@ from __future__ import annotations
 
 import json
 import logging
-from datetime import datetime
+from datetime import datetime, timezone
 from uuid import UUID, uuid4
 
 from legal_mcp.services import db
@@ -38,7 +38,7 @@ async def log_action(
                VALUES ($1, $2, $3, $4, $5, $6, $7)""",
             uuid4(), action, case_id, document_id,
             json.dumps(details or {}, ensure_ascii=False, default=str),
-            user, datetime.utcnow(),
+            user, datetime.now(timezone.utc),
         )
     logger.info("AUDIT: %s | case=%s | user=%s | %s", action, case_id, user,
                 json.dumps(details or {}, ensure_ascii=False)[:200])