docs: qualify plan-mode timing and workspace no-write claims

ds-review-bot round 3:
- set() after a turn's final step lands in a later turn (selection
  never forces continuation) — the same-turn phrasing overstated the
  guarantee; set() JSDoc + subsystem page (both languages).
- Workspace attach/insert/detach no-op claims now carry the
  filtered-candidate-prune caveat: mutate() durably prunes stale
  candidates even when the requested change is a no-op, a state the
  sessionIds contract explicitly permits; Workspace fence re-synced on
  both page sides; catalogs regenerated.

docs/subsystems/workspace.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 docs/subsystems/workspace.md
-workspace.md: bade3526964055d5bf4448265c5898f1e66a1fce
-workspace.zh.md: b0437e42b644c1ce11d9a667972f7b236cf4caa1
+workspace.md: 5614631e828e51f3b515ae4af17451bd9eda1dbb
+workspace.zh.md: 11e8f0207a8db8b7612d6672cfe744523490aef7