feat(settings): add API Route provider preset

[DennyHo0917]

Summary

Add API Route as a built-in preset in AI settings, following the small preset/changelog pattern from Requesty (#157) and Opper (#165).

• Preset ID/kind: api-route; display name: API Route.
• API compatibility: openai; base URL: https://global.api-route.com/v1.
• Reuse the existing model discovery, connection validation, credential storage, and OpenAI-compatible transport.
• Fix preset lookup when reopening an existing provider: match its exact kind first, then fall back to protocol compatibility for legacy entries. The previous combined predicate selected OpenAI before reaching later compatible presets.
• Record both changes in the existing changelog.

I maintain API Route. This removes manual endpoint setup for its users while keeping the change limited to the existing settings flow. Two files changed; no dependencies or backend changes.

Verification

Rebased onto the latest master, including the newly merged Opper preset.

On Node 24:

• npm run build: passed.
• npm run test:ci: 32 suites, 582 tests passed.
• npm run lint:check: passed.
• npm audit --audit-level=critical: passed.
• Evaluated the actual preset-selection expressions for all 15 preset IDs; exact-kind matching and the legacy OpenAI fallback passed.

Live gateway compatibility smoke checks: authenticated /models returned 60 IDs; a synthetic gpt-6.1-sol Chat Completions call returned SQLKIT_OK. This was an HTTP check, not a full Tauri end-to-end test. No database content or credentials are included in this PR.

Native Tauri launch and Rust/JDBC suites were not run locally for this frontend-only change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

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