fix: progress detection improvements (#141, #144) (#158)

* fix: progress detection improvements (#141, #144)

- Fix checkbox regex to exclude date entries like [2026-01-29] (#144)
- Add git commit detection: files changed in commits now count as progress (#141)
- Add 13 regression tests for progress detection and checkbox regex
- Update test count from 452 to 465

Fixes #141, Fixes #144

* fix(test): increase grep context to capture echo -1 line

* fix: count both committed and working tree changes as progress

When commits are made, now unions:
- Files changed in commits (loop_start_sha..current_sha)
- Unstaged changes (git diff HEAD)
- Staged changes (git diff --cached)

Uses sort -u to deduplicate before counting.

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Co-authored-by: Test User <test@example.com>

CLAUDE.md

@@ -432,7 +432,7 @@ Ralph uses advanced error detection with two-stage filtering to eliminate false
 | `test_cli_modern.bats` | 29 | Modern CLI commands (Phase 1.1) + build_claude_command fix |
 | `test_json_parsing.bats` | 45 | JSON output format parsing + Claude CLI format + session management + array format |
 | `test_session_continuity.bats` | 28 | Session lifecycle management + circuit breaker integration + issue #91 fix |
-| `test_exit_detection.bats` | 35 | Exit signal detection + EXIT_SIGNAL-based completion indicators |
+| `test_exit_detection.bats` | 53 | Exit signal detection + EXIT_SIGNAL-based completion indicators + progress detection |
 | `test_rate_limiting.bats` | 15 | Rate limiting behavior |
 | `test_loop_execution.bats` | 20 | Integration tests |
 | `test_edge_cases.bats` | 20 | Edge case handling |