feat(03-01): GEO-02 server half both directions — chat-keyboard fallback + GET /api/location + POST /api/location-fallback (claim-scoped)

- handlers/location-fallback.ts: requestLocationFallback (ReplyKeyboardMarkup request_location:true copy from strings.ts), recordSharedPin, registerLocationFallback (filters message.location, T-03-03)
- strings.ts: awaitingPin/shareLocationButton/pinReceived in en+ms (CS1 parity) — all bot copy stays in strings.ts
- bot.ts: createBot threads env.chat_sessions into the fallback handler; optional client fetch seam for tests; one-caller rule documented
- webhook.ts: GET /api/location relay + POST /api/location-fallback trigger, both resolve chat_id & locale from getClaimByToken CLAIM, never client input (T-03-01/26/27); telegram-send failure is category-only 502 (T-03-28)
- location-pin.test.mjs: LP1–LP14 (TTL contract, range guard, cross-user isolation both routes, locale split); LP12/LP13 patch node-fetch's cached default (grammy's node shim transport), then restore
- CS4 scope untouched (handlers/ not scanned); CS1 parity automatic

bot/src/i18n/strings.ts

@@ -28,6 +28,13 @@ export interface BotStrings {
   /** D-03: lists only commands that exist in this phase — derived lines
    *  ("cmd — description") feed the setMyCommands registration script. */
   helpMenu: string;
+  /** GEO-02: chat-keyboard fallback prompt — bot tells the user to share a pin. */
+  awaitingPin: string;
+  /** GEO-02: the reply-keyboard button label (request_location: true). */
+  shareLocationButton: string;
+  /** GEO-02: confirmation after the user's shared pin has been recorded
+   *  in the TTL-only location-pin KV (GEO-03). */
+  pinReceived: string;
 }
 
 export type Locale = "en" | "ms";
@@ -42,6 +49,9 @@ export const strings: Record<Locale, BotStrings> = {
       "What araharah never keeps: your location, your routes, your trip history, any profile about you.",
     helpMenu:
       "Commands:\n/help — How araharah works and what it keeps\n/privacy — What araharah stores and never stores",
+    awaitingPin: "Send me a pin in this chat and I'll use it as your starting point.",
+    shareLocationButton: "Share my location",
+    pinReceived: "Got it — your starting point is set.",
   },
   ms: {
     startIntro:
@@ -52,6 +62,9 @@ export const strings: Record<Locale, BotStrings> = {
       "Yang araharah tidak pernah simpan: lokasi anda, laluan anda, sejarah perjalanan anda, apa-apa profil tentang anda.",
     helpMenu:
       "Arahan:\n/help — Cara araharah berfungsi dan apa yang ia simpan\n/privacy — Apa yang araharah simpan dan tidak pernah simpan",
+    awaitingPin: "Hantar saya pin dalam chat ini dan saya akan gunakannya sebagai titik mula anda.",
+    shareLocationButton: "Kongsi lokasi saya",
+    pinReceived: "Baik — titik mula anda sudah ditetapkan.",
   },
 };