test(android): fix alarm counting logic and add screenshot capture

Fix alarm counting to correctly parse dumpsys output where app ID and
action appear on different lines. Add screenshot capture for test
diagnostics and create golden run documentation.

Test Harness Improvements:
- Fix get_plugin_alarm_count() to track app ID and action separately
  across alarm block lines (fixes false 0-count bug)
- Add show_plugin_alarms_compact() to display complete alarm blocks
- Add wait_for_stable_plugin_alarm_count() polling helper to reduce
  race condition false negatives
- Add take_screenshot() and take_failure_screenshot() helpers for
  automatic test state capture
- Integrate screenshots into TEST 0 at key checkpoints
- Update TEST 0 messaging to handle race conditions gracefully
- Add screenshots/ to .gitignore

Documentation:
- Create PHASE1_TEST0_GOLDEN.md with actual values from successful run
- Document expected script output, UI state, dumpsys shape, and logcat
  patterns
- Include pass/fail checklist for future test runs

This fixes the issue where alarm counting always returned 0 because the
AWK logic required app ID and action on the same line, but dumpsys
output has them on separate lines (header line has app ID, tag line
has action).

.gitignore

@@ -64,4 +64,5 @@ logs/
 .cache/
 *.lock
 *.bin
-workflow/
+workflow/
+screenshots/