fix: harden and de-slop the merged contribution batch

Follow-ups promised on merge, plus review findings on the batch itself:

- chat: task-tool output now respects the 512KiB render cap; quick-open
  icon is visible at rest on coarse pointers and reachable by keyboard
  (row keydown no longer swallows inner-button Enter/Space); composer
  inline-code decoration drops the metric-shifting padding; a btw fork
  send carries only the boundary instruction, never the promotion notice
- sync: cascade revert/unrevert aborts busy descendants, busy state is
  read from every child store at the moment of use; rule 9 documents
  redo clearing all descendant revert markers
- electron: renderer recovery keeps memory-eviction (a valid
  render-process-gone reason) and both windows share one
  attachRendererRecovery helper
- vscode: process registry is a thin re-export of the web module
  (provider-env-aliases precedent) with ordered register/unregister
  writes and an awaited close
- server/cli: managed-process registry takes injectable deps (fixes the
  unreaped-orphans ReferenceError), corrupt settings errors name the
  file, getWorktrees test restores console.warn
- tests: module-mock harnesses removed (AgentsSidebar, SettingsView
  mobile focus — behaviors stay live but uncovered, accepted trade),
  QuestionMarkdown asserts rendered DOM
- i18n: German gains the debug-panel request keys, Japanese/German drop
  removed worktree keys, Ukrainian unit spacing fixed
- changelog: Copilot AI Credits entries (main + VS Code)

packages/ui/src/lib/btw.ts

@@ -74,6 +74,23 @@ export const BTW_PROMOTION_NOTICE =
   + 'The btw constraints in the history above no longer apply: this is now the main thread, and the '
   + 'usual tool, sub-agent and workspace permissions are in force.';
 
+/**
+ * The btw framing texts a composer send carries.
+ *
+ * The boundary instruction rides with every send routed to an active btw fork,
+ * so the inherited transcript stays reference material for the whole side
+ * conversation. The promotion notice is the opposite case: it tells a promoted
+ * session that the btw constraints in its own history are lifted. A send routed
+ * to a fresh fork is never that session, so the two never travel together.
+ */
+export const buildBtwSyntheticTexts = (state: {
+  isBtwActive: boolean;
+  isPromotedBtwSession: boolean;
+}): string[] => {
+  if (state.isBtwActive) return [BTW_BOUNDARY_INSTRUCTION];
+  return state.isPromotedBtwSession ? [BTW_PROMOTION_NOTICE] : [];
+};
+
 /** The boundary as an `additionalParts` entry for `sendMessage`. */
 const btwBoundaryParts = (): Array<{ text: string; synthetic: true }> =>
   [{ text: BTW_BOUNDARY_INSTRUCTION, synthetic: true }];