chore: replace pino/pino-pretty with built-in logger

Drop 23 transitive dependencies by replacing pino + pino-pretty with a
~70-line logger that matches the same output format and API. All 80+
call sites work unchanged. Production deps now: @onecli-sh/sdk,
better-sqlite3, cron-parser.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -23,9 +23,7 @@
   "dependencies": {
     "@onecli-sh/sdk": "^0.2.0",
     "better-sqlite3": "11.10.0",
-    "cron-parser": "5.5.0",
-    "pino": "^9.6.0",
-    "pino-pretty": "^13.0.0"
+    "cron-parser": "5.5.0"
   },
   "devDependencies": {
     "@eslint/js": "^9.35.0",