Summary

Narrows broad except Exception catches to specific exception types
across 21 files, making errors surface loudly instead of being swallowed.

Why

CLAUDE.md requires "No Silent Fallbacks - Fail Loudly." Broad exception
catches hide real errors and make debugging harder. Each narrowing targets
the exact exception the code block can raise.

Linked issue

Refs #951

Changes

• JSON parsing → except (ValueError, json.JSONDecodeError)
• Numeric parsing → except ValueError
• File IO → except OSError
• Import-time → except ImportError
• Network libs → their specific request/network exceptions

Test plan

• python util/lint.py --all - no failures
• pytest tests/unit/ - all passing

Checklist

• I have linked a GitHub issue above.
• I have described why this change is being made.
• I have run linting and tests locally.
• No behavior changes - only exception type narrowing.