session-memory Phase 1: Codex adapter (T01) + multi-file merge (T03)

- adapters/common.py: shared Normalized + helpers (resolve_repo, classify_tool,
  jsonl iter, etc.); claude.py refactored to use it (Normalized re-exported)
- adapters/codex.py: rollout {timestamp,type,payload} parser; session_meta/
  response_item/event_msg mapping; flat call_id join; token_count cost;
  registered in ingest dispatch
- core/store.py: ingest() now merges multi-file sessions by content
  fingerprint, appends new events with offset seq (design OQ6); idempotent
- tests/test_codex_adapter.py, tests/test_merge.py

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

session_memory/ingest.py

@@ -19,13 +19,17 @@ from dataclasses import dataclass, field
 from typing import Any
 
 from .adapters import claude as claude_adapter
+from .adapters import codex as codex_adapter
 from .core import digest as digest_mod
 from .core.cursor import Cursors
 from .core.retention import RetentionConfig, sweep as retention_sweep
 from .core.store import Store
 
 # adapter dispatch by source name
-_ADAPTERS = {"claude": claude_adapter.parse_session}
+_ADAPTERS = {
+    "claude": claude_adapter.parse_session,
+    "codex": codex_adapter.parse_session,
+}
 
 
 @dataclass