chore: harden logger TZ, ffmpeg lifecycle and fix package metadata

- Logger.Timestamp now formats via Intl with timeZone Asia/Seoul, so
  the timestamp is correct regardless of the container/host TZ. The
  previous setHours(+9) hack assumed the system clock was UTC.
- Transcode.mp3BufferToPcmStream now attaches error/stderr handlers
  to the ffmpeg child process and its streams, swallows EPIPE on
  early downstream close, and force-kills on spawn error so failed
  conversions can't leak processes. Log level bumped from 'quiet'
  to 'error' so real ffmpeg errors surface.
- package.json homepage/bugs/repository pointed at github.com/tkrmagid/bot.ts
  which doesn't reflect this repo. Repoint to the actual Gitea origin.

package.json

@@ -2,13 +2,13 @@
   "name": "tts_bot",
   "version": "0.0.1",
   "description": "discord bot with typescript",
-  "homepage": "https://github.com/tkrmagid/bot.ts#readme",
+  "homepage": "https://git.tkrmagid.kr/tkrmagid/tts_bot",
   "bugs": {
-    "url": "https://github.com/tkrmagid/bot.ts/issues"
+    "url": "https://git.tkrmagid.kr/tkrmagid/tts_bot/issues"
   },
   "repository": {
     "type": "git",
-    "url": "git+https://github.com/tkrmagid/bot.ts.git"
+    "url": "git+https://git.tkrmagid.kr/tkrmagid/tts_bot.git"
   },
   "license": "ISC",
   "author": "tkrmagid",