feat(logger): integrate Winston with console and file transports

[teethaking]

Closes #246

Type of Change

• New feature (non-breaking change which adds functionality)

What Changed

Replaces the previous console-based logger.ts with a professional Winston
implementation. The existing API is fully preserved — no other files need updating.

Transports

Transport	When Active	Output
Console	Always	Colorized, timestamped, human-readable
File: errors.log	Production / LOG_TO_FILE=true	JSON, error level only, 10MB × 5 rotations
File: combined.log	Production / LOG_TO_FILE=true	JSON, all levels, 20MB × 5 rotations

API — Backward Compatible

All existing call sites continue to work unchanged:

logger.debug("message", meta?)
logger.info("message", meta?)
logger.warn("message", meta?)
logger.error("message", error?, meta?)
logger.event("EVENT_TYPE", data)

What Improved vs Before

• ✅ Color-coded levels — cyan info, yellow warn, red error
• ✅ Timestamps in YYYY-MM-DD HH:mm:ss.SSS format
• ✅ Error stacks automatically captured and structured
• ✅ Persistent file logs in production with auto-rotation
• ✅ Silent in NODE_ENV=test — no noisy test output
• ✅ LOG_LEVEL env var controls verbosity without code changes

Environment Variables

Variable	Default	Description
LOG_LEVEL	debug (dev) / info (prod)	Minimum log level to output
LOG_TO_FILE	false	Enable file transport outside production
LOG_DIR	<cwd>/logs	Directory for log files

Checklist

• I have read the CONTRIBUTING.md guidelines
• My commits follow the Conventional Commits specification
• My commits are atomic and represent singular logical changes
• I have self-reviewed my own code
• I have tested my changes locally and verified they pass linting and builds