feat(quick-start): add workflow-backed creation flow

[huyanxius]

Title: feat(quick-start): add workflow-backed creation flow

Dependency

• Stacked on focused PR feat(workflow-run): add frontend execution foundation #6 and upstream PR feat(workflow-run): add frontend execution foundation 1024XEngineer/Windup#72; do not merge before the WorkflowRun foundation lands.
• Base branch feat/workflow-run-core is the head of PR feat(workflow-run): add frontend execution foundation #6.
• This focused PR contains only the Quick Start vertical slice: 3 files in 2 atomic commits.
• After feat(workflow-run): add frontend execution foundation 1024XEngineer/Windup#72 lands, rebase this branch onto the updated base before marking it ready.

Feature Description

• Replace the Quick Start placeholder with a responsive natural-language creation surface.
• Create and observe one WorkflowRun on /quick-start/:runId without redirecting to Workflow Editor.
• Show real running, failure, interruption, and character-template candidate states from the shared WorkflowRun.

Implementation Approach

• Prepare a real Project first, then delegate execution, recovery, subscriptions, and interruption to the existing WorkflowController.
• Keep Project creation behind an injected page-level boundary; unconfigured production wiring fails explicitly and never invents a project ID or Mock success.
• Reuse the LiveDemo input/progress/result rhythm without copying its fake timers, hardcoded outputs, routes, or runtime.

Testing

• npm run format:check — passed (49 files)
• npm run lint — passed
• npm run typecheck — passed
• npm run test -- --reporter=dot — passed (6 files, 37 tests)
• npm run build — passed
• git diff --check feat/workflow-run-core...HEAD — passed
• Local browser — desktop/mobile render passed; explicit unavailable state and zero console errors confirmed

Follow-ups

• Wire real ProjectApis, GenerationApis, and TaskApis after the backend address and DTO fixtures are confirmed.
• Candidate selection and later workflow steps remain separate vertical slices.

[CX] Prompt & Review

• Prompt summary: implement the next Quick Start slice on the current reduced architecture, reuse only safe LiveDemo presentation, and preserve the frontend-only WorkflowRun model.
• AI review: layering, unnecessary complexity, hardcoding, async error boundaries, and test validity were checked; no blocker remained.
• Human review: pending; keep this PR in Draft.

Refs 1024XEngineer#58