chore: v2.8.12 — clone queue and progress, session defaults, chat agents, drops as @ mentions

Whole tree from parallel sessions, plus the version bump:
- Clone: a queue with live progress (Add workspace and extra folders),
  clones run under nice/ionice so the machine stays responsive.
- Settings → AI tools → Session defaults: a new session's default
  permission mode / bypass per account.
- Chat lists the background subagents that have not reported back yet.
- A file pasted or dropped into a claude pane goes in as an @ mention.
- Changes panel: say why amend/undo is refused on a pushed commit.
- openapi.yaml regenerated (Artifacts, Host, resumeById).

client/src/i18n/locales/en/settings.json

@@ -1307,6 +1307,20 @@
     "labelDesc": "A Claude or Codex session first shows its conversation like Claude Desktop, with a message box, instead of its terminal. Each session then keeps its own view: the chat/terminal button beside a pane's split buttons switches it. Permission prompts and menus still need the terminal.",
     "saveFailed": "Could not save: {{message}}"
   },
+  "sessionDefaults": {
+    "title": "Session defaults",
+    "description": "What a new session starts with in a workspace's prompt box. Saved for your account only; a pick in the prompt box changes only that one session.",
+    "claudeMode": "Claude Code permission mode",
+    "claudeModeDesc": "Bypass permissions lets every new Claude session run any tool without asking.",
+    "codexSandbox": "Codex sandbox",
+    "codexApproval": "Codex approval",
+    "codexBypass": "Codex: YOLO mode",
+    "codexBypassDesc": "Every new Codex session starts in YOLO mode — `--dangerously-bypass-approvals-and-sandbox`: no sandbox, no approvals.",
+    "confirmTitle": "Make bypass the default for {{tool}}?",
+    "confirmBody": "Every new {{tool}} session you start will run commands and edit files without asking, until you change this back. Use it only with folders and prompts you trust.",
+    "confirmLabel": "Make it the default",
+    "codexConfirmTitle": "Make YOLO the default for Codex?"
+  },
   "agentInstructions": {
     "title": "My agent instructions",
     "description": "Your own rules in Markdown — coding style, language, workflow. Every new session in a workspace you own starts with them, before that workspace's own instructions. Saved for your account only; sessions already running keep what they started with.",