[Story]: Create project + connect data sources in one flow

[adoLime]

User Story

As an Admin, I want to create a project and connect its data sources in a single flow (wizard), so that I don't have to do project creation and source connection as two separate steps on different pages.

Context & Motivation

• Type: Functional (Project administration UX)
• Parent epic: 03 EPIC - Connectors & Artifact Ingestion #52 (03 EPIC – Connectors & Artifact Ingestion)
• Teams: team:frontend (wizard), team:backend (small follow-ups only)
• Problem: Today project creation (AdminProjectController POST /api/v1/admin/projects, [Story]: Admin project management (create / delete projects + assign PMs) #197) and source connection (GithubConnectorController POST /api/v1/github/connect, [Story]: GitHub repository connector v0 (commits, files, issues, PR metadata) #159) live on separate pages. The Admin has to create the project first, navigate to the Data Ingestion page, then connect sources one by one. Both steps should be combined in a single flow.

Acceptance Criteria

Combined flow (Admin)

• Admin can start a "Create project" wizard from the admin view.
• Step 1 — Project details: name, PM assignment (reuses [Story]: Admin project management (create / delete projects + assign PMs) #197 API).
• Step 2 — Data sources (optional): Admin can add GitHub repositories to the new project in the same flow, either by entering owner + name directly, or via the discovery flow from [Story]: GitHub org/user discovery & multi-repo ingestion selection #244 (org/user → repo list).
• Admin can skip Step 2 and finish with a project but no sources — the classic flow stays available.
• On finish, the project is created first; each selected source is then connected and scoped to the new project's ID.

Partial failure handling

• If project creation succeeds but a source connection fails, the project remains created; the failed source is shown with an error message and a retry action.
• If project creation fails, no sources are connected.

General

• Empty / loading / error states; i18n (en/de).
• Works in light and dark themes; keyboard focus remains visible.