Add time-based orchestration, state management, diffing and logging

- config: add overrideTime for testing (HH:MM string)
- state.ts: daily state persistence (reference, lastKnown, sentAt10)
- differ.ts: detect text changes and sold-out changes between menu snapshots
- logger.ts: append timestamped changes to logs/YYYY-MM-DD.log
- index.ts: full cron logic — before 10 log only, at 10 send TG, after 10
  send on text change; sold-out always to TG without log; exit after 14:00
- .gitignore: add state/ and logs/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

config/default.ts

@@ -14,6 +14,7 @@ export interface TelegramConfig {
 export interface Config {
   days: DayUrls
   devMode: boolean
+  overrideTime: string | null
   telegram: TelegramConfig
 }
 
@@ -26,6 +27,7 @@ const config: Config = {
     friday:    "",
   },
   devMode: false,
+  overrideTime: null,
   telegram: {
     botToken: "",
     chatId:   "",