codegraph status stays silent when package.json alone adds or drops a framework #3007

#2941 has a sync record the frameworks that came or went since the last full index, so that codegraph status recommends a re-index. But a sync detects frameworks again only when it extracts a file (filesToIndex.length === 0 ? undefined : refreshFrameworkDetection(...)). An edit to package.json alone therefore records nothing.

Repro (upstream main 01e0ac3)

1. Create a project with package.json {"dependencies":{}} and src/server.js containing const express = require('express'); const app = express(); app.get('/hello', …).
2. Run codegraph init. There are no routes, as expected, since Express isn't a dependency.
3. Add "express": "^4.0.0" to package.json, then run codegraph sync and codegraph status --json.

Expected: frameworksChangedSinceIndex: { added: ['express'] } and reindexRecommended: true. A fresh index finds GET /hello.

Actual: frameworksChangedSinceIndex: null and reindexRecommended: false. /hello stays missing until a manual re-index.

SvelteKit behaves the same way: adding @sveltejs/kit leaves goto('/login') in an unchanged +layout.svelte unlinked.

A long-running process (the MCP server's watcher) doesn't pick up the framework either, for the same reason.