[P1] Silent exception swallowing — add logging throughout

[ShadowWalkerNC]

Summary

Multiple routes silently swallow exceptions:

except Exception:
    posts = []

except Exception:
    profile = {}

Impact

Production bugs are invisible. Sentry can't catch what's never re-raised or logged. Debugging becomes guesswork.

Fix

Log before swallowing, or let Sentry capture properly:

except Exception:
    app.logger.exception("Failed to load post history for user %s", uid)
    return jsonify({'success': False, 'error': 'Server error', 'posts': []})

Audit all except Exception blocks across app.py and all modules and add app.logger.exception() at minimum.

Effort: ~2 hours

Part of full audit: #1