refs/heads/handle-mobile-pull-request-issues (#6598)

* feat(mobile): add commit failure recovery panel with AI fix action

- Surfaces a "Commit failed" panel with a one-tap AI fix button when a
  git commit fails in the source control view or PR creation flow
- Detects commit failures specifically during the committing progress
  step and captures staged entries and commit message for context
- Extracts commit failure summary and prompt logic into
  `src/shared/source-control-commit-failure.ts` and PR checks prompt
  into `src/shared/pr-checks-fix-prompt.ts` so both desktop and mobile
  share the same implementations
- Adds auto-find of an available Metro port starting from 8081 and
  extracts expo CLI bootstrap into `mobile-expo-cli.mjs` shared by
  `start-emulator` and a new `start-expo.mjs` wrapper

* Share source-control AI prompts and simplify mobile PR actions

- Extract conflict, check-fixing, and commit-failure prompt builders
  to shared modules for reuse by both desktop and mobile.
- Configure Metro in the mobile package to watch and bundle modules
  from the repository-root shared directory.
- Remove the desktop-style merge method picker from the mobile PR
  actions panel, opting to use repository defaults automatically.
- Refactor mobile hosted review creation and git preparation logic
  into dedicated helper files.

src/shared/source-control-commit-failure-agent-command.ts

@@ -0,0 +1,22 @@
+import {
+  DEFAULT_SOURCE_CONTROL_ACTION_COMMAND_TEMPLATES,
+  renderSourceControlActionCommandTemplate
+} from './source-control-ai-actions'
+
+export function buildCommitFailureAgentCommandInput({
+  promptOverride,
+  commandInputTemplate,
+  basePrompt
+}: {
+  promptOverride?: string
+  commandInputTemplate?: string | null
+  basePrompt: string
+}): string {
+  return (
+    promptOverride ??
+    renderSourceControlActionCommandTemplate(
+      commandInputTemplate ?? DEFAULT_SOURCE_CONTROL_ACTION_COMMAND_TEMPLATES.fixCommitFailure,
+      { basePrompt }
+    )
+  ).trim()
+}