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/cli/handlers/session-init.ts

@@ -6,7 +6,7 @@
 
 import type { EventHandler, NormalizedHookInput, HookResult } from '../types.js';
 import { ensureWorkerRunning, workerHttpRequest } from '../../shared/worker-utils.js';
-import { getProjectName } from '../../utils/project-name.js';
+import { getProjectContext } from '../../utils/project-name.js';
 import { logger } from '../../utils/logger.js';
 import { HOOK_EXIT_CODES } from '../../shared/hook-constants.js';
 import { isProjectExcluded } from '../../utils/project-filter.js';
@@ -42,7 +42,7 @@ export const sessionInitHandler: EventHandler = {
     // Use placeholder so sessions still get created and tracked for memory
     const prompt = (!rawPrompt || !rawPrompt.trim()) ? '[media prompt]' : rawPrompt;
 
-    const project = getProjectName(cwd);
+    const project = getProjectContext(cwd).primary;
     const platformSource = normalizePlatformSource(input.platform);
 
     logger.debug('HOOK', 'session-init: Calling /api/sessions/init', { contentSessionId: sessionId, project });