Improve Fluid Intelligence settings

[altic-dev]

Description

Improves the Fluid Intelligence provider settings UI and runtime controls.

• Aligns the Fluid Intelligence provider row with the other AI provider controls.
• Adds the same edit flow with reset verification, delete model, Fast startup, and Fluid-1 Boost controls.
• Adds a configurable dictation window with a 4K default, 8K cap, safer help text, persistence, backup/restore support, and tests.
• Keeps the Fluid Intelligence inline editor from showing the generic API-key editor at the same time.

Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality not to work as expected)
• 🧹 Chore
• 📝 Documentation update

Related Issues

• N/A

Testing

• Tested on Intel Mac
• Tested on Apple Silicon Mac
• Tested on macOS 15.5
• Ran linter locally: swiftlint --strict --config .swiftlint.yml Sources
• Ran formatter locally: swiftformat --config .swiftformat Sources
• Ran FI dev build locally: sh build_with_FI_incremental.sh
• Ran OSS build locally: FLUID_INTELLIGENCE=0 INSTALL_APP=0 LAUNCH_APP=0 sh build_dev.sh
• Ran targeted settings tests for Fluid Intelligence boost and dictation window persistence/clamping

Notes

• RELEASE_NOTES_1.6.2.md was updated locally and left uncommitted because release notes files are intentionally gitignored.
• Private Fluid Intelligence bridge/runtime files remain local/private and are not included in this PR.

Screenshots / Video

• Not attached.