fix: Handle non-string Playwright snapshots without crashing

[meirk-brd]

• Ensure filter_snapshot returns the raw _snapshotForAI output when it isn’t text, avoiding TypeErrors.
• Simplify parse_playwright_snapshot by removing redundant type check now that the guard/fallback lives in filter_snapshot.
• Keeps ARIA parsing intact for string snapshots while letting DOM snapshot logic proceed on unexpected types.