fix: Update project name when session already exists in createSDKSession

**Problem:**
- Sessions created with empty project names couldn't be updated
- INSERT OR IGNORE skipped updates when session already existed
- Context-hook couldn't find observations (WHERE project = 'claude-mem')
- 364 observations had empty project names

**Root Cause:**
createSDKSession() used INSERT OR IGNORE for idempotency, but never
updated project/prompt fields when session already existed. If SAVE hook
created session first (with empty project), NEW hook couldn't fix it.

**Solution:**
When INSERT is ignored (session exists), UPDATE project and user_prompt
if we have non-empty values. This ensures project name gets set even
when session was created by SAVE hook or with incomplete data.

**Impact:**
- New sessions will always have correct project name
- Backfilled 364 historical observations with project='claude-mem'
- Context injection will now work (finds observations by project)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/services/sqlite/SessionStore.ts

@@ -1013,6 +1013,17 @@ export class SessionStore {
 
     // If lastInsertRowid is 0, insert was ignored (session exists), so fetch existing ID
     if (result.lastInsertRowid === 0 || result.changes === 0) {
+      // Session exists - UPDATE project and user_prompt if we have non-empty values
+      // This fixes the bug where SAVE hook creates session with empty project,
+      // then NEW hook can't update it because INSERT OR IGNORE skips the insert
+      if (project && project.trim() !== '') {
+        this.db.prepare(`
+          UPDATE sdk_sessions
+          SET project = ?, user_prompt = ?
+          WHERE claude_session_id = ?
+        `).run(project, userPrompt, claudeSessionId);
+      }
+
       const selectStmt = this.db.prepare(`
         SELECT id FROM sdk_sessions WHERE claude_session_id = ? LIMIT 1
       `);