feat(FN-2403): add project setup step to onboarding flow

- Introduce a new "project-setup" onboarding step between GitHub and first-task actions
- Gate first-task navigation on project selection and add contextual setup-wizard guidance
- Centralize ordered onboarding step definitions in shared state and reuse them for navigation/progress labels
- Extract ModelOnboardingModal styles into a dedicated component CSS file and update tests/mocks for the new step order

packages/dashboard/app/components/model-onboarding-state.ts

@@ -5,7 +5,7 @@
  * from where they left off if they dismiss the modal without completing.
  */
 
-export type OnboardingStep = "ai-setup" | "github" | "first-task" | "complete";
+export type OnboardingStep = "ai-setup" | "github" | "project-setup" | "first-task" | "complete";
 
 interface OnboardingState {
   currentStep: OnboardingStep | string; // string allows for future unknown steps
@@ -38,6 +38,12 @@ const DEFAULT_COMPLETED = false;
 const DEFAULT_STEP_DATA: Partial<Record<OnboardingStep, Record<string, unknown>>> = {};
 const DEFAULT_POST_ONBOARDING_DISMISSED_AT: string | undefined = undefined;
 
+/**
+ * Ordered onboarding flow steps before completion.
+ * Keep this list in sync with ModelOnboardingModal's stepper rendering and navigation.
+ */
+export const ONBOARDING_FLOW_STEPS = ["ai-setup", "github", "project-setup", "first-task"] as const;
+
 /**
  * Step labels for display in the resume card.
  * Fallback for unknown step IDs uses the raw key with title-case formatting.
@@ -45,6 +51,7 @@ const DEFAULT_POST_ONBOARDING_DISMISSED_AT: string | undefined = undefined;
 export const ONBOARDING_STEP_LABELS: Record<OnboardingStep, string> = {
   "ai-setup": "AI Setup",
   github: "GitHub",
+  "project-setup": "Project",
   "first-task": "First Task",
   complete: "Complete",
 };