fix: upgrade whisper-rs to 0.16.0 and fix Windows build

[TheChiragKaushik]

Description

This PR fixes the Windows build which was completely broken due to a
whisper-rs-sys struct layout change. The underlying whisper.cpp C library
restructured its internal structs, making whisper-rs 0.13.2 incompatible
with the latest whisper-rs-sys bindings on Windows.

Changes made:

• Upgraded whisper-rs from 0.13.2 to 0.16.0 across all platforms
• Removed hardcoded vulkan feature from Windows dependencies (Vulkan
  SDK is not installed by default on Windows and was causing build failures
  for most users it remains available as an opt-in feature flag via
  --features vulkan)
• Updated whisper API calls in whisper_engine.rs to match the new 0.16.0 API:
  • set_suppress_non_speech_tokens() → set_suppress_nst()
  • full_get_segment_text_lossy() → get_segment() returning Option
  • full_get_segment_t0/t1() → get_segment().start/end_timestamp()
  • Removed invalid ? operator from full_n_segments() which returns i32
  • Fixed WhisperContext::new_with_params path deref (&* instead of &)
• Fixed Tauri command re-exports in summary/mod.rs and
  summary/summary_engine/mod.rs to use direct module paths instead of
  cmd variants which are incompatible with Tauri 2.11

Related Issue

[Link to the issue this PR addresses (e.g., "Fixes #123")]

Type of Change

• Bug fix

Testing

• Manual testing performed
• Built and ran successfully on Windows 11 with Intel Iris Xe (CPU-only mode)
• App launches, transcription works, summary generation works

Checklist

• Code follows project style
• Self-reviewed the code

Additional Notes

This was tested on Windows 11 with VS 2022 Build Tools. The build requires
VS 2022 Build Tools with "Desktop development with C++" workload due to
ort-sys (ONNX Runtime) requiring newer MSVC runtime symbols not present
in VS 2019.

[medeng-dev]

Build succeeds on Windows 11 with VS 2022 Build Tools (CPU-only mode). App launches correctly. Haven't fully tested transcription and summary functionality yet, but the compilation error with whisper-rs 0.13.2 is resolved.