feat(ui): add OperationStatus feedback primitive and OperationIndicator control

Foundation for long-running-operation feedback (P0-1). OperationStatus tracks
IsRunning/ShowIndicator(300ms grace)/Elapsed/IsStalled(60s since last Report)
via an injectable TimeProvider, no static timer. OperationIndicator binds a
status to the shared spinner style. Pre-provisions ops.* locale keys for
groups A and C; no ViewModel wired up yet.

src/ClaudeDo.Localization/locales/en.json

@@ -692,6 +692,56 @@
     "lists": { "localSuffix": "{0} / local", "smartMyDay": "My Day", "smartImportant": "Important", "smartPlanned": "Planned", "virtualQueue": "Queue", "virtualRunning": "Running", "virtualReview": "Review", "newList": "New list" },
     "repoImport": { "loadFailed": "Couldn't load remembered folders: {0}", "saveFailed": "Couldn't save folders: {0}" }
   },
+  "ops": {
+    "stalledHint": "Still running — worker hasn't responded in a while",
+    "merge": {
+      "merging": "Merging…",
+      "verifying": "Running the list's verify command… ({0})"
+    },
+    "review": {
+      "submitting": "Submitting for review…",
+      "rejecting": "Rejecting…",
+      "parking": "Parking…",
+      "previewing": "Loading preview…"
+    },
+    "worktrees": {
+      "refreshing": "Refreshing…",
+      "cleaningUp": "Cleaning up finished worktrees…",
+      "resetting": "Resetting worktree…",
+      "forceRemoving": "Force-removing worktree…",
+      "batchMerging": "Merging {0}/{1}…"
+    },
+    "skills": {
+      "installing": "Cloning skill…",
+      "updating": "Updating skill…",
+      "restoringDefaults": "Restoring default agents…"
+    },
+    "onlineInbox": {
+      "signingIn": "Signing in…"
+    },
+    "repoImport": {
+      "scanning": "Scanning repositories…"
+    },
+    "updateCheck": {
+      "checking": "Checking for updates…"
+    },
+    "reports": {
+      "generatingWeekly": "Generating report…",
+      "runningDailyPrep": "Running daily prep…"
+    },
+    "planning": {
+      "buildingIntegrationBranch": "Building integration branch…",
+      "loadingAggregate": "Loading combined preview…",
+      "finalizing": "Finalizing plan…",
+      "queuingSubtasks": "Queuing subtasks…"
+    },
+    "worker": {
+      "startupRecovery": "Recovering…",
+      "creatingWorktree": "Creating worktree…",
+      "rebasingAfterMerge": "Rebasing other worktrees…",
+      "maintainingWorktrees": "Maintaining worktrees…"
+    }
+  },
   "usage": {
     "pill": {
       "empty": "Usage –",