fix(cli): improve whisper-cpp install guidance and add doctor check (#1681)

- Platform-specific install instructions for Linux (apt) and Windows
  (releases page / cmake) instead of a generic "see GitHub" fallback
- Export getInstallInstructions so doctor can reuse it
- Add whisper-cpp check to `hyperframes doctor` after the Environment
  check — reports path when found, shows install hint when missing

packages/cli/src/whisper/manager.ts

@@ -151,10 +151,16 @@ export function findWhisper(): WhisperResult | undefined {
   return findFromEnv() ?? findFromSystem() ?? findBuiltBinary();
 }
 
-function getInstallInstructions(): string {
+export function getInstallInstructions(): string {
   if (platform() === "darwin") {
     return "brew install whisper-cpp";
   }
+  if (platform() === "linux") {
+    return "Build from source: https://github.com/ggml-org/whisper.cpp#building (requires cmake and a C compiler)";
+  }
+  if (platform() === "win32") {
+    return "Build with cmake: https://github.com/ggml-org/whisper.cpp#building";
+  }
   return "See https://github.com/ggml-org/whisper.cpp#building";
 }