signaling: type TURN secrets via committed .d.ts (fix CI typecheck)

`wrangler types` only emits TURN_KEY_ID / TURN_API_TOKEN into the generated
worker-configuration.d.ts when they're present in the local (gitignored)
.env — so a dev machine typechecks but a fresh CI checkout doesn't, and
`env.TURN_KEY_ID` fails. These are production-only secrets (set via
`wrangler secret put`), never in wrangler.jsonc, so wrangler can't generate
their types in CI by design.

Declare them in a committed no-import .d.ts that merges into the global
`Env` (typed `string` to match wrangler's own output, so the local
generated declaration and this one coexist without conflict). No secret
values committed; CI and dev both typecheck.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: yyq1025

packages/signaling/src/env.d.ts

@@ -0,0 +1,13 @@
+// TURN-minting secrets, set in production via `wrangler secret put`
+// (TURN_KEY_ID / TURN_API_TOKEN — see wrangler.jsonc). They are NOT in
+// wrangler.jsonc, and the only local source that feeds `wrangler types`
+// (a gitignored `.env`) is absent in CI — so the generated
+// `worker-configuration.d.ts` carries them on a dev machine but NOT in a
+// fresh CI checkout. Declaring them here merges them into the global `Env`
+// unconditionally, keeping `env.TURN_*` typed everywhere without ever
+// committing a value. A no-import .d.ts is a global script, so this
+// `interface Env` augments the generated one via declaration merging.
+interface Env {
+  TURN_KEY_ID: string;
+  TURN_API_TOKEN: string;
+}