feat(FN-800): auto-generate model preset IDs and remove manual ID editing

- Add slugify and generatePresetId utilities with collision handling for unique preset IDs
- Remove manual ID input field from preset editor UI in SettingsModal
- Auto-generate preset IDs server-side from name on creation
- Simplify Header tests by removing ID-related test cases
- Deduplicate tablet header controls tests by importing from shared Header tests
- Remove unused CSS rules for removed ID input field
- Update reviewer to pass through preset ID generation logic

packages/dashboard/app/components/__tests__/SettingsModal.test.tsx

@@ -523,7 +523,6 @@ describe("SettingsModal", () => {
     await user.click(screen.getByText("Add Preset"));
 
     await user.type(screen.getByLabelText("Name"), "Budget");
-    expect((screen.getByLabelText("ID") as HTMLInputElement).value).toBe("budget");
 
     await user.click(screen.getByText("Save preset"));
     await user.click(screen.getByText("Save"));