… threading (#900)

* feat(session): make commit two-phase with async memory extraction

Session commit now returns immediately after archiving messages (Phase 1).
Summary generation and memory extraction (Phase 2) run in the background
via asyncio.create_task(), returning a task_id for polling progress.

- Add get_task() API across all client layers for querying background task status
- get_session() auto-creates session if it does not exist
- Remove wait parameter and telemetry from commit endpoint
- Add .done completion marker to archive directories
- Update docs (EN/ZH) and tests for new two-phase flow

* feat(session): add .meta.json persistence and auto_create control for get_session

SessionService.get() now defaults to auto_create=False, raising NotFoundError
for missing sessions. A new SessionMeta dataclass tracks created_at, updated_at,
message_count, commit_count, memories_extracted (by category), last_commit_at,
and cumulative llm_token_usage. Meta is persisted to .meta.json and updated on
add_message, commit Phase 1 (message clear), and commit Phase 2 completion
(token usage, memory counts via bind_telemetry). All client layers
(local/async/sync/HTTP) and API docs updated accordingly.

* fix: remove session vectorize

* support commit for openclaw-plugin (#902)

Made-with: Cursor

* fix: reuse latest archive overview in session context

Thread the latest completed archive overview into archive summary generation and memory extraction, and simplify search context assembly to current messages plus the latest archive overview.

Co-Authored-By: Claude Opus 4.6

* refactor: session overview

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Co-authored-by: AutoCoder <wulf234@163.com>