fix review findings: stale seam docs + race-free doneFor test helper

Codex review of the PR2 diff caught doc/comment sites doc-sync does not gate
(core-data-structures prose) and a latent test-helper race:
- docs/core-data-structures/persistence.md + bash.md, sqlite README, and two
  source comments (coordinator.ts, jsonl.spec.ts) still listed the removed
  has/delete/get/list methods — updated to the surviving four-method
  persistence surface and the get/list-free bash seam.
- doneFor(ctx, id) attached its onTaskDone listener lazily, after the task
  could already have closed (e.g. `true`), so it could miss the completion and
  hang. Replaced with trackCompletions(ctx): one eagerly-installed listener
  (mounted in setup() before any task starts) records every completion, and
  doneFor resolves immediately for an already-finished task or on completion
  otherwise. Race-free, and there is no get-by-id seam left to poll instead.

packages/session-persistence/session-persistence-sqlite/README.md

@@ -6,7 +6,7 @@ A SQLite durable session-persistence backend — a second `SessionPersistence` i
 
 ## Storage model
 
-Each `SessionEvent` maps 1:1 onto a row in an `events` table `(session_id, seq, type, time, data)` — `data` is the event payload as JSON text, so the row shape is the event verbatim (including `assistant/chunk`, keeping `seq` contiguous). Out-of-log metadata (`SessionHeader`) lives in a `sessions` row. A `sessions` row is written only by the first `append` — its existence is the lazy-materialization signal (`has`/`list` report exactly the sessions that have a row), so no separate column is needed.
+Each `SessionEvent` maps 1:1 onto a row in an `events` table `(session_id, seq, type, time, data)` — `data` is the event payload as JSON text, so the row shape is the event verbatim (including `assistant/chunk`, keeping `seq` contiguous). Out-of-log metadata (`SessionHeader`) lives in a `sessions` row. A `sessions` row is written only by the first `append` — its existence is the lazy-materialization signal (`list` reports exactly the sessions that have a row), so no separate column is needed.
 
 The repo targets Node ≥ 24 (the root `engines` field), which includes the stable `node:sqlite` module. The database opens with `foreign_keys = ON` (so `ON DELETE CASCADE` drops a session's events with its row) and `journal_mode = WAL`. The table-layout version is stored in `PRAGMA user_version` and checked on open: a fresh database is stamped with the current `SCHEMA_VERSION`; a database written by any other, incompatible build (a non-current `user_version`, older or newer) is rejected rather than opened against an unknown layout — there is no migration (unreleased software).