fix: stop draining queue on /clear (remove SessionEnd shim) (#2136)

* fix: stop draining queue on /clear (and on every other SessionEnd)

The SessionEnd hook was wired to session-complete on Claude Code, Gemini
CLI, the transcripts processor, the OpenCode plugin, and OpenClaw. All of
those paths called POST /api/sessions/complete, which marked the session
completed and abandoned every still-pending observation in the queue.

So typing /clear (or logging out, or quitting) wiped in-flight work that
the worker was perfectly happy to keep processing on its own.

Removed the entire shim:
- Deleted SessionEnd hook block in plugin/hooks/hooks.json
- Deleted src/cli/handlers/session-complete.ts and its registry entry
- Deleted POST /api/sessions/complete route + Zod schema in SessionRoutes
- Removed call from transcripts processor handleSessionEnd
- Removed call from opencode-plugin session.deleted handler
- Removed Gemini SessionEnd → session-complete mapping
- Removed openclaw scheduleSessionComplete + completionDelayMs + timer state
- Updated tests + comments accordingly

Explicit user-initiated deletion (DELETE /api/sessions/:id and
POST /api/sessions/:sessionDbId/complete from the viewer UI) still works
via SessionCompletionHandler.completeByDbId — that's the only path that
should drain the queue.

The worker self-completes via its SDK-agent generator's finally-block, so
no external completion call is needed.

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

* docs: clarify opencode-plugin session.deleted is in-memory cleanup only

Greptile P2: file-level header still implied session.deleted called the
worker. Now it only cleans up the local contentSessionIdsByOpenCodeSessionId
map; worker self-completes via the SDK-agent generator finally-block.

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

---------

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

src/services/worker-service.ts

@@ -806,11 +806,8 @@ export class WorkerService implements WorkerRef {
         } else {
           // Successful completion with no pending work — finalize then drop
           // in-memory state. finalizeSession flips sdk_sessions.status to
-          // 'completed', drains orphaned pendings, broadcasts; idempotent so
-          // the later POST /api/sessions/complete from the Stop hook is a
-          // no-op. Without this, hooks-disabled installs (and any session
-          // whose Stop hook fails before /api/sessions/complete) leave the
-          // DB row permanently 'active'.
+          // 'completed', drains orphaned pendings, broadcasts. This is the
+          // sole completion path now that the SessionEnd hook shim is gone.
           session.restartGuard?.recordSuccess();
           session.consecutiveRestarts = 0;
           this.completionHandler.finalizeSession(session.sessionDbId);
@@ -1225,7 +1222,7 @@ async function main() {
       if (!platform || !event) {
         console.error('Usage: claude-mem hook <platform> <event>');
         console.error('Platforms: claude-code, cursor, gemini-cli, raw');
-        console.error('Events: context, session-init, observation, summarize, session-complete, user-message');
+        console.error('Events: context, session-init, observation, summarize, user-message');
         process.exit(1);
       }