batch4.1-5.1: dedup audit, archive 400 fix, sidebar Delete, landing-page enrichment, auto-name tool-call fix

- Fastify global empty-JSON-body parser fixes archive/unarchive/stop 400s
- Removed redundant local sessionEvents.emit at all 5+2 sites with server-side WS publishers; added dedupe guards in useSidebar/Workspace/Project handlers
- Sidebar session right-click adds Delete (destructive) with confirm Dialog
- Session.tsx navigates away on session_deleted/session_archived for the active session
- SessionLandingPage chat rows show message_count, effective_context_tokens, last_message_preview via LATERAL joins on GET /api/sessions/:id/chats
- Workspace.tsx pane drag-to-reorder using native HTML5 events (no new deps)
- CompactCard: Copy toast, Send-to-chat with target chat name, empty-state in share popover, Re-run button
- auto_name.ts: filter count gate and assistant-fetch by content <> '' so tool-call assistant rows don't trip the once-and-only-once guard
- Adds CLAUDE.md and apps/web/src/lib/format.ts

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

apps/server/src/index.ts

@@ -24,6 +24,22 @@ async function main() {
     logger: { level: config.LOG_LEVEL },
   });
 
+  // Allow empty JSON bodies on POSTs that don't take a body (archive, unarchive, stop, etc.).
+  // Default Fastify parser throws FST_ERR_CTP_EMPTY_JSON_BODY on empty string.
+  app.removeContentTypeParser(['application/json']);
+  app.addContentTypeParser('application/json', { parseAs: 'string' }, (_req, body, done) => {
+    const str = (body as string) ?? '';
+    if (str.trim().length === 0) {
+      done(null, {});
+      return;
+    }
+    try {
+      done(null, JSON.parse(str));
+    } catch (err) {
+      done(err as Error, undefined);
+    }
+  });
+
   const sql = getSql(config);
   await applySchema(sql);
   app.log.info('database schema applied');