feat(logger): add browser entry path for client-side logging

[frytg]

Summary

Investigated whether the default @frytg/logger entry can be optimized for browser use. It cannot: bundling with esbuild for --platform=browser fails on node:os, node:process, and Winston's Node dependencies.

Adds a dedicated @frytg/logger/browser entry for frontend apps (Vue, React, etc.) as a structured console replacement:

• Avoids Node built-ins and Winston
• Logs caller-provided fields only (level, message, source, data, error) — no server deployment env injection
• Uses import.meta.env.DEV / MODE === 'development' for debug level and pretty-printed JSON
• Bundles to ~3.1 KB (esbuild) vs. the default entry which does not bundle at all

Usage

// Server (unchanged)
import logger from '@frytg/logger';

// Browser
import logger from '@frytg/logger/browser';

logger.info('user signed in', {
  source: 'components/LoginForm',
  data: { method: 'oauth' },
});

How to test

• deno run test / npx tsx --test logger/*.test.ts — all logger tests pass
• npx esbuild logger/logger-browser.ts --bundle --platform=browser --format=esm --outfile=/tmp/logger-browser-bundle.js — bundles successfully (~3.1 KB)
• npx esbuild logger/logger.ts --bundle --platform=browser — still fails (expected; default entry remains server-only)

Follow-ups

• Forward browser logs to a backend endpoint in a future version
• Consider extracting shared syslog level constants if both entries need to stay in sync long-term