Add process_uuid to sqlite logs (#11534)

## Summary
This PR is the first slice of the per-session `/feedback` logging work:
it adds a process-unique identifier to SQLite log rows.

It does **not** change `/feedback` sourcing behavior yet.

## Changes
- Add migration `0009_logs_process_id.sql` to extend `logs` with:
  - `process_uuid TEXT`
  - `idx_logs_process_uuid` index
- Extend state log models:
  - `LogEntry.process_uuid: Option<String>`
  - `LogRow.process_uuid: Option<String>`
- Stamp each log row with a stable per-process UUID in the sqlite log
layer:
  - generated once per process as `pid:<pid>:<uuid>`
- Update sqlite log insert/query paths to persist and read
`process_uuid`:
  - `INSERT INTO logs (..., process_uuid, ...)`
  - `SELECT ..., process_uuid, ... FROM logs`

## Why
App-server runs many sessions in one process. This change provides a
process-scoping primitive we need for follow-up `/feedback` work, so
threadless/process-level logs can be associated with the emitting
process without mixing across processes.

## Non-goals in this PR
- No `/feedback` transport/source changes
- No attachment size changes
- No sqlite retention/trim policy changes

## Testing
- `just fmt`
- CI will run the full checks

codex-rs/state/migrations/0010_logs_process_id.sql

@@ -0,0 +1,3 @@
+ALTER TABLE logs ADD COLUMN process_uuid TEXT;
+
+CREATE INDEX idx_logs_process_uuid ON logs(process_uuid);