fix: use parent project name for worktree observation writes (#1820)

* fix: use parent project name for worktree observation writes (#1819)

Observations and sessions from git worktrees were stored under
basename(cwd) instead of the parent repo name because write paths
called getProjectName() (not worktree-aware) instead of
getProjectContext() (worktree-aware). This is the same bug as
#1081, #1317, and #1500 — it regressed because the two functions
coexist and new code reached for the simpler one.

Fix: getProjectContext() now returns parentProjectName as primary
when in a worktree, and all four write-path call sites now use
getProjectContext().primary instead of getProjectName().

Includes regression test that creates a real worktree directory
structure and asserts primary === parentProjectName.

* fix: address review nitpicks — allProjects fallback, JSDoc, write-path test

- ContextBuilder: default projects to context.allProjects for legacy
  worktree-labeled record compatibility
- ProjectContext: clarify JSDoc that primary is canonical (parent repo
  in worktrees)
- Tests: add write-path regression test mirroring session-init/SessionRoutes
  pattern; refactor worktree fixture into beforeAll/afterAll

* refactor(project-name): rename local to cwdProjectName and dedupe allProjects

Addresses final CodeRabbit nitpick: disambiguates the local variable
from the returned `primary` field, and dedupes allProjects via Set
in case parent and cwd resolve to the same name.

---------

Co-authored-by: Ethan Hurst <ethan.hurst@outlook.com.au>

src/services/worker/http/routes/SessionRoutes.ts

@@ -22,7 +22,7 @@ import { PrivacyCheckValidator } from '../../validation/PrivacyCheckValidator.js
 import { SettingsDefaultsManager } from '../../../../shared/SettingsDefaultsManager.js';
 import { USER_SETTINGS_PATH } from '../../../../shared/paths.js';
 import { getProcessBySession, ensureProcessExit } from '../../ProcessRegistry.js';
-import { getProjectName } from '../../../../utils/project-name.js';
+import { getProjectContext } from '../../../../utils/project-name.js';
 import { normalizePlatformSource } from '../../../../shared/platform-source.js';
 
 export class SessionRoutes extends BaseRouteHandler {
@@ -507,7 +507,7 @@ export class SessionRoutes extends BaseRouteHandler {
   private handleObservationsByClaudeId = this.wrapHandler((req: Request, res: Response): void => {
     const { contentSessionId, tool_name, tool_input, tool_response, cwd } = req.body;
     const platformSource = normalizePlatformSource(req.body.platformSource);
-    const project = typeof cwd === 'string' && cwd.trim() ? getProjectName(cwd) : '';
+    const project = typeof cwd === 'string' && cwd.trim() ? getProjectContext(cwd).primary : '';
 
     if (!contentSessionId) {
       return this.badRequest(res, 'Missing contentSessionId');