Add Windows exe icon, clean release filenames, fix Linux build

- Embed microphone icon in Windows exe via winresource
- Rename release artifacts to friendly names (linux-x86_64, windows-x86_64)
- Fix warn macro import for Linux build
- Add cargo PATH to release script
- Fix tea CLI asset upload syntax

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

assets/mouth.rc

@@ -0,0 +1 @@
+1 ICON "assets/mouth.ico"