sync: ingest local sources when there are no remote ones

[kaihirota]

What happens today

In SyncManager.runSync() the scan, the ingest and the stats all sit inside
if (remoteSources.length > 0):

if (remoteSources.length > 0) {
  const syncResult = await syncAllRemoteSources(...);
  const sources = this.config.sources.map(expandPath);
  sources.push(...syncResult.cachedPaths);
  const files = scanSources(sources, this.config.exclude);
  const ingestResult = ingestSessions(files, this.db, false);
  ...
}

So a machine with no remote sources configured runs the auto-sync timer on every interval and
ingests nothing. defaultConfig() has remote_sources: [], so that is the default: serve
appears to be keeping the database current and is not.

What this changes

sources is lifted out of the branch, and the scan, ingest and stats run after it. Remote
paths are still appended when there are remotes.

Two tests cover it: local sources are ingested with no remotes configured, and
lastIngestStats reports what was done.

Also

src/web/server.test.ts writes to the user's real config path, and its teardown only
restored a config that had existed beforehand. With no previous config the fixture was left
in place and became the live one. It is now removed in that case.

bun run check passes: 94 tests, typecheck clean.