fix(tools): bound the shaped-append side channel; total error containment; recorded spill snapshot

Responding to ds-review-bot round 2 on #661:

- logWork is bounded: past maxParallelSubCalls pending shaped-append tasks
  the ordered commit lane holds (Promise.race drains one), so a slow spill
  backend backpressures the run instead of accumulating unbounded pending
  I/O and retained results. Tasks self-remove on settlement; run
  settlement still drains every task inside the open turn. New spill test
  drives three oversized reads against a hung backend at cap 1 and proves
  the third dispatch cannot start until a save drains.
- shapeDispatchLog's catch uses errorMessage() (total), so a thrown value
  with a throwing toString cannot escape the containment and lose the
  settle event.
- CodeDispatchLog.content documented as the RENDERED result projection
  (native tool/result vocabulary), not what the program received — the
  program gets the structured value; doc pair + type-equiv re-synced.
- New RECORDED tui-agent snapshot scenario code-mode-dispatch-spill: the
  real Loader-visible composition (worker runtime + spill-local + policy)
  drives an oversized bash sub-call end-to-end; replay proves the durable
  dispatch copy is bounded to preview + locator while the program value
  stays whole (the outer result carries just the line count).

Agent Note updated (both languages).

.agents/notes/implemented/feature/2026-07-26-code-dispatch-log-spill.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write
-2026-07-26-code-dispatch-log-spill.md: 2668c195a43ae1f6011c09413338a23caf75401e
-2026-07-26-code-dispatch-log-spill.zh.md: e084ae80d7fed864c7f296b1fd6db713acf7a2b0
+2026-07-26-code-dispatch-log-spill.md: 65af7808c493867cb13042a4f169ffdf05eb4538
+2026-07-26-code-dispatch-log-spill.zh.md: e1293e62f9de9860300428c5c0d25c5404dc76f9