fix(merge): conventional merge-commit default and live verify progress

The merge commit message was hand-rolled per caller ("Merge task: <title>",
"Merge <branch>", "Merge subtask") and ignored the task's commit type. Every
caller now passes a blank message and TaskMergeService fills in
CommitMessageBuilder.BuildMerge -> {commitType}(list-slug): merge <title> plus the
ClaudeDo-Task trailer; the merge modal prefills it from GetMergeTargets.

A merge whose list has a verify command holds the MergeTask call for minutes (5m46s
on this repo), during which the modal only disabled its button - no spinner, no
message, so a landed merge looked like a dead app. TaskMergeService now broadcasts
MergeProgress(taskId, phase, elapsedSeconds) for the merging and verifying phases
(re-reported every 30s) plus a WorkerLog line when verify starts; the modal shows a
spinner and the localized phase.

src/ClaudeDo.Localization/locales/en.json

@@ -673,7 +673,7 @@
     "tasksIsland": { "completedHeader": "COMPLETED", "completedHeaderCount": "COMPLETED · {0}", "planningOpenFailed": "Couldn't open planning session: {0}", "planningResumeFailed": "Couldn't resume planning session: {0}", "approveFailed": "Approve & merge failed: {0}", "cancelReviewFailed": "Cancel review failed: {0}", "sendToQueueFailed": "Send to queue failed: {0}", "queuePlanBlockedInteractive": "Can't queue the plan — {0} has an open interactive session and must be closed first.", "moveRunningRejected": "Can't move a running task to another list.", "moveWorktreeRejected": "Can't move — this task has an active worktree pointing at its current repo.", "moveRepoConfirm": "Different repos — {0} → {1}. Move the task anyway?", "moveConfirmUnavailable": "Can't move — the confirmation dialog isn't available.", "quickClaudeNoWorkingDir": "This list has no working directory configured.", "quickClaudeDirMissing": "Working directory no longer exists: {0}" },
     "diff": { "loadFailed": "Failed to load diff: {0}", "noChanges": "No changes to show.", "unavailable": "Diff no longer available — commit range incomplete." },
     "planningDiff": { "hubError": "Could not build combined preview (hub error).", "conflict": "Cannot build combined preview: subtask {0} conflicts with an earlier subtask ({1} files).", "buildFailed": "Could not build combined preview: {0}" },
-    "merge": { "commitMessage": "Merge task: {0}", "workerOfflineBranches": "Worker offline — cannot list branches.", "loadBranchesFailed": "Failed to load branches: {0}", "merged": "Merged.", "conflict": "Merge conflict — target branch restored. Resolve manually or via Continue, then retry.", "blocked": "Blocked: {0}", "verifyFailed": "Merge landed, but the list's verify command failed — the task was kept out of Done.", "untrackedCollision": "Merge refused — it would overwrite an untracked file in the target working directory.", "unknownStatus": "Unknown status: {0}", "mergeFailed": "Merge failed: {0}" },
+    "merge": { "commitMessage": "chore: merge {0}", "progressMerging": "Merging…", "progressVerifying": "Running the list's verify command… ({0})", "workerOfflineBranches": "Worker offline — cannot list branches.", "loadBranchesFailed": "Failed to load branches: {0}", "merged": "Merged.", "conflict": "Merge conflict — target branch restored. Resolve manually or via Continue, then retry.", "blocked": "Blocked: {0}", "verifyFailed": "Merge landed, but the list's verify command failed — the task was kept out of Done.", "untrackedCollision": "Merge refused — it would overwrite an untracked file in the target working directory.", "unknownStatus": "Unknown status: {0}", "mergeFailed": "Merge failed: {0}" },
     "conflictResolution": { "vsCodeError": "Could not launch VS Code: {0}. Paths are listed above — copy them manually.", "subtaskPrefix": "Conflicts in subtask: {0}", "targetPrefix": "Merging into: {0}" },
     "settingsModal": { "workerOffline": "Worker offline — settings read-only.", "saveFailed": "Save failed: {0}" },
     "onlineInbox": { "workerOffline": "Worker offline — cannot load config.", "saved": "Config saved.", "saveFailed": "Save failed: {0}", "signedIn": "Signed in successfully.", "signedInNoRole": "Signed in, but this account is missing the 'user' role in Zitadel — online sync will be rejected until the role is granted in the ClaudeDo project.", "signInFailed": "Sign-in failed: {0}", "signedOut": "Signed out.", "signOutFailed": "Sign-out failed: {0}" },