test(app/e2e): add composer-attachments spec (8 behaviors) (#734)

* test(app/e2e): add composer-attachments spec covering 8 attachment behaviors

Restores E2E coverage for composer attachment behaviors dropped in PR #720:
plus-menu visibility, GitHub combobox lazy search, image lightbox, pill render,
pill removal (with hover-reveal), queue-on-running-agent, review-pill suppression
(test.fixme pending store seeding bridge), and Escape interrupt draft preservation.

Includes accessibilityRole="button" on QueuedMessageRow Pressables (was rendering
as generic, breaking role-based selectors) and an opt-in E2E debug surface on
useWorkspaceAttachmentsStore (localStorage gated, needed for the fixme test).

* refactor(app/e2e): unslop composer-attachments spec and helpers

Remove dead `expectComposerLocked` export (never imported), trim verbose
JSDoc on `pressInterruptShortcut`, and correct the test.fixme comment
which said the store wasn't window-exposed (it is, as of the parent commit).

* fix(app/e2e): address PR #734 review blockers for composer-attachments spec

- Remove window.__paseoWorkspaceAttachmentsStore exposure (hard ban on internal
  state injection)
- Merge helpers/composer-attachments.ts into helpers/composer.ts; delete old file
- Add openGithubWorkspace, selectGithubOption, expectGithubAttachmentPill,
  expectComposerDisabled, expectAttachButtonDisabled helpers to composer.ts
- Extract delayBrowserAgentCreatedStatus from new-workspace.spec.ts into
  helpers/new-workspace.ts so it can be shared
- Add real GH issue/PR pill tests using createTempGithubRepo fixtures
- Rewrite lock-state test to assert textarea disabled + attach button disabled
  during in-flight workspace creation (submitBehavior=preserve-and-lock)
- Add test.fixme with detailed explanation for workspace-review pill (requires
  diff pane automation not yet in E2E harness)
- Add test.fixme for browser-element pill (Electron-only, not testable in
  headless Chromium)

* refactor(app/e2e): unslop composer helpers and spec after blockers fix

- Remove AI section headers from composer.ts (not in project convention)
- Fix fillComposerDraft: drop redundant click() before fill()
- Fix selectGithubOption: extract locator to local var instead of double getByTestId()
- Use clickNewWorkspaceButton in lock-state test instead of raw Create button locator
- Drop obvious PNG constant comment

packages/app/src/components/composer.tsx

@@ -461,6 +461,7 @@ function QueuedMessageRow({ item, onEdit, onSendNow }: QueuedMessageRowProps) {
           onPress={handleEdit}
           style={styles.queueActionButton}
           accessibilityLabel="Edit queued message"
+          accessibilityRole="button"
         >
           <ThemedPencil size={ICON_SIZE.sm} uniProps={iconForegroundMapping} />
         </Pressable>
@@ -468,6 +469,7 @@ function QueuedMessageRow({ item, onEdit, onSendNow }: QueuedMessageRowProps) {
           onPress={handleSendNow}
           style={QUEUE_SEND_BUTTON_STYLE}
           accessibilityLabel="Send queued message now"
+          accessibilityRole="button"
         >
           <ArrowUp size={ICON_SIZE.sm} color="white" />
         </Pressable>