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-jsonl/tests/jsonl.spec.ts

@@ -629,8 +629,8 @@ describe('SessionPersistenceJsonl: edge cases', () => {
     const a = meta('dup-id', '/projA')
     await ctx.sessionPersistence.create(a)
     await ctx.sessionPersistence.append(a.id, oneTurnLog())
-    // A fresh backend creating the SAME id under cwd B must still refuse: load/
-    // has identify by id across all buckets, so a second log would make resume
+    // A fresh backend creating the SAME id under cwd B must still refuse: load
+    // identifies by id across all buckets, so a second log would make resume
     // nondeterministic. create scans every bucket, not just meta.cwd's.
     const ctx2 = new Context()
     await ctx2.plugin(SessionStore)