fix: add whisper gpu fallback and compute mode

[BlindMaster24]

No description provided.

[BlindMaster24]

@cjpais Done!

[BlindMaster24]

cjpais/transcribe-rs#34

[BlindMaster24]

Some GPUs don’t support Vulkan, so Whisper GPU mode can fail to start. This adds a CPU fallback and lets users manually choose CPU mode or auto.

[BlindMaster24]

was checked

[VirenMohindra]

hey @BlindMaster24, thanks for putting this together. before we can review this properly, could you fill out the PR template? we have a lot of open PRs and inflight work right now so following the conventions in .github/PULL_REQUEST_TEMPLATE.md helps us triage and review efficiently

specifically we'd need

• a human written description explaining what problem you noticed and why this change matters
• related issues / discussions (if any)
• how you tested the changes
• the AI assistance disclosure checkbox
• screenshots (if needed)

PRs without the template filled out are unlikely to get accepted. happy to review once that's in place!

[BlindMaster24]

@cjpais ?

[cjpais]

@BlindMaster24 I have a lot of code to review, I only have limited time to review things every day

[BlindMaster24]

@cjpais Ok, waiting.