Add secondary transcription shortcut and language

Please confirm you have done the following:

• I have searched existing issues and pull requests (including closed ones) to ensure this isn't a duplicate
• I have read CONTRIBUTING.md

If this is a feature or change that was previously closed/rejected:

• I have explained in the description below why this should be reconsidered
• I have gathered community feedback (link to discussion below)

Human Written Description

I wanted Handy to support two different transcription languages depending on which shortcut is pressed. The current behavior only allows one shortcut and one language, which makes switching between languages unnecessarily slow for multilingual use. This change adds a second shortcut and a second language setting, while keeping the existing primary flow intact and making the shortcut/model behavior more consistent.

Related Issues/Discussions

Fixes #

Discussion:

Community Feedback

I have not linked a discussion yet.

Testing

• Ran cargo test --manifest-path src-tauri/Cargo.toml
• Ran bun run build
• Ran bun run check:translations
• Verified that the secondary shortcut can use a separate language
• Verified that the secondary shortcut is unbound by default
• Verified that resetting the secondary shortcut clears it back to no shortcut
• Verified that model-dependent language settings are disabled while a model switch is in progress

Screenshots/Videos (if applicable)

Not included.

AI Assistance

• No AI was used in this PR
• AI was used (please describe below)

If AI was used:

• Tools used: codex-cli / GPT-5.4 xhigh
• How extensively: AI was used to help analyze the codebase, implement the changes, run checks, and refine the final code and PR text. I reviewed the changes locally and fixed issues before opening this PR.