Replace bare exception fallbacks with specific logging

[VaibhavDangaich]

Fixes #194.

Summary

This PR replaces bare except Exception fallbacks in optional-path code with narrower exception handling and debug logging, while preserving the existing graceful fallback behavior.

What Changed

• narrowed SQLite fallbacks in:
  • code_review_graph/graph.py
  • code_review_graph/wiki.py
  • code_review_graph/visualization.py
  • code_review_graph/migrations.py
  • code_review_graph/tools/context.py
• narrowed parser/metadata/runtime fallbacks in:
  • code_review_graph/parser.py
  • code_review_graph/tsconfig_resolver.py
  • code_review_graph/registry.py
  • code_review_graph/cli.py
  • code_review_graph/eval/benchmarks/search_quality.py
• added debug logging so optional failures are visible during debugging
• kept the existing fallback return values such as {}, [], None, and "dev"

Tests

• added tests/test_cli.py for _get_version() fallback logging
• added logging/fallback coverage in tests/test_graph.py

Verification

• ./.venv/bin/python -m pytest tests --tb=short -q
• result: 618 passed, 5 skipped, 2 xpassed

Notes

This change is intentionally scoped to the issue-reported bare fallback handlers and does not alter existing except Exception as e paths that already log or return structured errors.