feat(telegram): add sticker support with vision caching

Add support for receiving and sending Telegram stickers:

Inbound:
- Receive static WEBP stickers (skip animated/video)
- Process stickers through dedicated vision call for descriptions
- Cache vision descriptions to avoid repeated API calls
- Graceful error handling for fetch failures

Outbound:
- Add sticker action to send stickers by fileId
- Add sticker-search action to find cached stickers by query
- Accept stickerId from shared schema, convert to fileId

Cache:
- Store sticker metadata (fileId, emoji, setName, description)
- Fuzzy search by description, emoji, and set name
- Persist to ~/.clawdbot/telegram/sticker-cache.json

Config:
- Single `channels.telegram.actions.sticker` option enables both
  send and search actions

🤖 AI-assisted: Built with Claude Code (claude-opus-4-5)
Testing: Fully tested - unit tests pass, live tested on dev gateway
The contributor understands and has reviewed all code changes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/auto-reply/templating.ts

@@ -1,4 +1,5 @@
 import type { ChannelId } from "../channels/plugins/types.js";
+import type { StickerMetadata } from "../telegram/bot/types.js";
 import type { InternalMessageChannel } from "../utils/message-channel.js";
 import type { CommandArgs } from "./commands-registry.types.js";
 import type {
@@ -64,6 +65,8 @@ export type MsgContext = {
   MediaPaths?: string[];
   MediaUrls?: string[];
   MediaTypes?: string[];
+  /** Telegram sticker metadata (emoji, set name, file IDs, cached description). */
+  Sticker?: StickerMetadata;
   OutputDir?: string;
   OutputBase?: string;
   /** Remote host for SCP when media lives on a different machine (e.g., clawdbot@192.168.64.3). */