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/context/ContextBuilder.ts

@@ -10,7 +10,7 @@ import { homedir } from 'os';
 import { unlinkSync } from 'fs';
 import { SessionStore } from '../sqlite/SessionStore.js';
 import { logger } from '../../utils/logger.js';
-import { getProjectName } from '../../utils/project-name.js';
+import { getProjectContext } from '../../utils/project-name.js';
 
 import type { ContextInput, ContextConfig, Observation, SessionSummary } from './types.js';
 import { loadContextConfig } from './ContextConfigLoader.js';
@@ -129,11 +129,12 @@ export async function generateContext(
 ): Promise<string> {
   const config = loadContextConfig();
   const cwd = input?.cwd ?? process.cwd();
-  const project = getProjectName(cwd);
+  const context = getProjectContext(cwd);
+  const project = context.primary;
   const platformSource = input?.platform_source;
 
-  // Use provided projects array (for worktree support) or fall back to single project
-  const projects = input?.projects || [project];
+  // Use provided projects array (for worktree support) or fall back to all known projects
+  const projects = input?.projects ?? context.allProjects;
 
   // Full mode: fetch all observations but keep normal rendering (level 1 summaries)
   if (input?.full) {