feat(storage): move desktop SQLite ownership into a storage utility process

Main no longer opens desktop business SQLite. A single utility-process
storage owner holds the Assistant, Knowledge, attachment, document-result,
remote-binding and native model-ledger databases and runs whole domain
transactions; Main and Runtime callers use explicit async domain operations.

- Remove the Main readWithFallback path and the supervision worker's
  separate business write connection; manifests are scanned read-only and
  committed by the sole writer.
- Remote events are ACKed only after commit; process loss reports
  unconfirmed writes instead of replaying them.
- Use native utilityProcess messaging with one in-flight bound (32) and
  ordered waiting instead of capacity rejection and retries.
- Start the storage process before the window so startup overlaps.
- Keep short tool output in memory and store full output once in owned
  storage; paging, branching, restart and deletion reuse that copy.
- Put required runtime launch files under goodbuddy-prefixed owned temp
  directories and reclaim confirmed stale ones; stop writing duplicate
  parsed.md.
- Add lint guards for SQLite ownership and architecture, concurrency
  acceptance fixtures, and maintenance/architecture documentation.

Validation: typecheck and lint pass. Alternating baseline (edf019aa) vs
candidate runs show no regression on single-session, C01, C02, C04 and a
5-minute C06; Main p99 drops from ~21 ms to ~16.7 ms under concurrency.
Fresh portable copy (1.75M events) upgrade content unchanged; real-model
output paging passes with 4 external requests. Full npm test runs had
1-9 different timing-sensitive failures per run that pass when rerun.
Not covered: C03 review publication, C07 source body, app-level C05.

src/main/agent/create-runtime.test.ts

@@ -72,6 +72,19 @@ function settings(
 }
 
 describe('createAgentRuntime model compatibility', () => {
+  it('forwards the existing attachment owner to direct-model output consumers', async () => {
+    const backingStore = {
+      create: vi.fn(), append: vi.fn(), finish: vi.fn(), read: vi.fn(), release: vi.fn()
+    }
+    const outputAdopt = vi.fn()
+    const outputStore = { backingStore }
+    const runtime = createAgentRuntime(process.cwd(), settings(), { outputStore, outputAdopt })
+    try {
+      expect(runtime).toMatchObject({ options: { outputStore, outputAdopt } })
+      expect(backingStore.create).not.toHaveBeenCalled()
+    } finally { await runtime.dispose() }
+  })
+
   it('passes the desktop failure observer to local OpenCode', async () => {
     const observeFailure = vi.fn()
     const runtime = createAgentRuntime(process.cwd(), settings({ provider: 'opencode' }), { observeFailure })