feat: Add Minimax provider support

[Phototonic]

Description

This PR adds complete Minimax provider support to YapCap, enabling users to track their Minimax API token usage directly from the COSMIC panel applet.

Changes

• New Provider: Full Minimax integration with API key-based authentication
• UI/UX Improvements: Added explicit "API Key" and "Account" labels to Minimax login form fields for better clarity
• Icon Assets: Added proper Minimax branding with dedicated icons for default and reversed variants
• Documentation: Updated README.md and docs/spec.md to include Minimax provider information
• Localization: Added Minimax-related translation strings

Additional Context

We initially attempted to add Kimi provider support as well but were unsuccessful due to current account and API limitations. The Kimi-related commits have been removed, keeping only the functional Minimax support.

Type of Change

• New feature
• Bug fix
• Breaking change
• Refactor
• Cosmetic
• Documentation update

Pre-flight Checklist

• Code compiles without errors
• All tests pass (352/352)
• Changes follow repository coding guidelines
• Documentation updated
• No merge conflicts with main branch

[TopiCsarno]

Hi, thanks for the contribution!
I've enabled CI for this PR.

Please check that these checks pass

cargo fmt --all -- --check
cargo test --all
just check

One early functional note from testing: I tried a normal MiniMax sk-api-* key with purchased Credits. The quota endpoints returned HTTP 200, but with:

{
"base_resp": {
"status_code": 2062,
"status_msg": "no active token plan subscription"
},
"model_remains": null
}

The app currently reports this as a generic parse failure. The implementation should parse base_resp.status_code and surface the MiniMax API message clearly. Once CI is green, I’ll take another pass at the MiniMax-specific behavior.

[Phototonic]

Pushed some changes to fix up failing CI checks, as well as some changes to hopefully handle the generic parse failure for the minimax API correctly.