fix(telegram): retry polling on all transient errors, not just 409 (#1397)

A single ETIMEDOUT/ECONNRESET/DNS failure during long-polling rejected
bot.start(); the catch block returned and polling stopped permanently.
The MCP server process stayed alive (stdin keeps it running), so outbound
reply/react tools kept working — but the bot was deaf to inbound messages
until a full restart. Users see 'typing...' then nothing, indistinguishable
from the harness-side gate bug.

Now all errors retry with the same capped backoff (max 15s). attempt resets
to 0 in onStart so backoff doesn't accumulate across a long-running session.

Co-authored-by: Claude <noreply@anthropic.com>

external_plugins/telegram/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "telegram",
   "description": "Telegram channel for Claude Code \u2014 messaging bridge with built-in access control. Manage pairing, allowlists, and policy via /telegram:access.",
-  "version": "0.0.5",
+  "version": "0.0.6",
   "keywords": [
     "telegram",
     "messaging",