refactor: move Telegram channel implementation to extensions/ (#45635)

* refactor: move Telegram channel implementation to extensions/telegram/src/

Move all Telegram channel code (123 files + 10 bot/ files + 8 channel plugin
files) from src/telegram/ and src/channels/plugins/*/telegram.ts to
extensions/telegram/src/. Leave thin re-export shims at original locations so
cross-cutting src/ imports continue to resolve.

- Fix all relative import paths in moved files (../X/ -> ../../../src/X/)
- Fix vi.mock paths in 60 test files
- Fix inline typeof import() expressions
- Update tsconfig.plugin-sdk.dts.json rootDir to "." for cross-directory DTS
- Update write-plugin-sdk-entry-dts.ts for new rootDir structure
- Move channel plugin files with correct path remapping

* fix: support keyed telegram send deps

* fix: sync telegram extension copies with latest main

* fix: correct import paths and remove misplaced files in telegram extension

* fix: sync outbound-adapter with main (add sendTelegramPayloadMessages) and fix delivery.test import path

extensions/telegram/src/fetch.env-proxy-runtime.test.ts

@@ -0,0 +1,58 @@
+import { createRequire } from "node:module";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const require = createRequire(import.meta.url);
+const EnvHttpProxyAgent = require("undici/lib/dispatcher/env-http-proxy-agent.js") as {
+  new (opts?: Record<string, unknown>): Record<PropertyKey, unknown>;
+};
+const { kHttpsProxyAgent, kNoProxyAgent } = require("undici/lib/core/symbols.js") as {
+  kHttpsProxyAgent: symbol;
+  kNoProxyAgent: symbol;
+};
+
+function getOwnSymbolValue(
+  target: Record<PropertyKey, unknown>,
+  description: string,
+): Record<string, unknown> | undefined {
+  const symbol = Object.getOwnPropertySymbols(target).find(
+    (entry) => entry.description === description,
+  );
+  const value = symbol ? target[symbol] : undefined;
+  return value && typeof value === "object" ? (value as Record<string, unknown>) : undefined;
+}
+
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+
+describe("undici env proxy semantics", () => {
+  it("uses proxyTls rather than connect for proxied HTTPS transport settings", () => {
+    vi.stubEnv("HTTPS_PROXY", "http://127.0.0.1:7890");
+    const connect = {
+      family: 4,
+      autoSelectFamily: false,
+    };
+
+    const withoutProxyTls = new EnvHttpProxyAgent({ connect });
+    const noProxyAgent = withoutProxyTls[kNoProxyAgent] as Record<PropertyKey, unknown>;
+    const httpsProxyAgent = withoutProxyTls[kHttpsProxyAgent] as Record<PropertyKey, unknown>;
+
+    expect(getOwnSymbolValue(noProxyAgent, "options")?.connect).toEqual(
+      expect.objectContaining(connect),
+    );
+    expect(getOwnSymbolValue(httpsProxyAgent, "proxy tls settings")).toBeUndefined();
+
+    const withProxyTls = new EnvHttpProxyAgent({
+      connect,
+      proxyTls: connect,
+    });
+    const httpsProxyAgentWithProxyTls = withProxyTls[kHttpsProxyAgent] as Record<
+      PropertyKey,
+      unknown
+    >;
+
+    expect(getOwnSymbolValue(httpsProxyAgentWithProxyTls, "proxy tls settings")).toEqual(
+      expect.objectContaining(connect),
+    );
+  });
+});