feat(workspaces): per-account tenancy + AI access keys + Cursor integration

Adds logical multi-tenancy on top of Coolify + Gitea so every Vibn
account gets its own isolated tenant boundary, and exposes that
boundary to AI agents (Cursor, Claude Code, scripts) through
per-workspace bearer tokens.

Schema (additive, idempotent — run /api/admin/migrate once after deploy)
  - vibn_workspaces: slug, name, owner, coolify_project_uuid,
    coolify_team_id (reserved for when Coolify ships POST /teams),
    gitea_org, provision_status
  - vibn_workspace_members: room for multi-user workspaces later
  - vibn_workspace_api_keys: sha256-hashed bearer tokens
  - fs_projects.vibn_workspace_id: nullable FK linking projects
    to their workspace

Provisioning
  - On first sign-in, ensureWorkspaceForUser() inserts the row
    (no network calls — keeps signin fast).
  - On first project create, ensureWorkspaceProvisioned() lazily
    creates a Coolify Project (vibn-ws-{slug}) and a Gitea org
    (vibn-{slug}). Failures are recorded on the row, not thrown,
    and POST /api/workspaces/{slug}/provision retries.

Auth surface
  - lib/auth/workspace-auth.ts: requireWorkspacePrincipal() accepts
    either a NextAuth session or "Authorization: Bearer vibn_sk_...".
    The bearer key is hard-pinned to one workspace — it cannot
    reach any other tenant.
  - mintWorkspaceApiKey / listWorkspaceApiKeys / revokeWorkspaceApiKey

Routes
  - GET    /api/workspaces                         list
  - GET    /api/workspaces/[slug]                  details
  - POST   /api/workspaces/[slug]/provision        retry provisioning
  - GET    /api/workspaces/[slug]/keys             list keys
  - POST   /api/workspaces/[slug]/keys             mint key (token shown once)
  - DELETE /api/workspaces/[slug]/keys/[keyId]     revoke

UI
  - components/workspace/WorkspaceKeysPanel.tsx: identity card,
    keys CRUD with one-time secret reveal, and a "Connect Cursor"
    block with copy/download for:
      .cursor/rules/vibn-workspace.mdc — rule telling the agent
        about the API + workspace IDs + house rules
      ~/.cursor/mcp.json — MCP server registration with key
        embedded (server URL is /api/mcp; HTTP MCP route lands next)
      .env.local — VIBN_API_KEY + smoke-test curl
  - Slotted into existing /[workspace]/settings between Workspace
    and Notifications cards (no other layout changes).

projects/create
  - Resolves the user's workspace (creating + provisioning lazily).
  - Repos go under workspace.gitea_org (falls back to GITEA_ADMIN_USER
    for backwards compat).
  - Coolify services are created inside workspace.coolify_project_uuid
    (renamed {slug}-{appName} to stay unique within the namespace) —
    no more per-Vibn-project Coolify Project sprawl.
  - Stamps vibn_workspace_id on fs_projects.

lib/gitea
  - createOrg, getOrg, addOrgOwner, getUser
  - createRepo now routes /orgs/{owner}/repos when owner != admin

Also includes prior-turn auth hardening that was already in
authOptions.ts (CredentialsProvider for dev-local, isLocalNextAuth
cookie config) bundled in to keep the auth layer in one consistent
state.

.env.example
  - Documents GITEA_API_URL / GITEA_API_TOKEN / GITEA_ADMIN_USER /
    GITEA_WEBHOOK_SECRET and COOLIFY_URL / COOLIFY_API_TOKEN /
    COOLIFY_SERVER_UUID, with the canonical hostnames
    (git.vibnai.com, coolify.vibnai.com).

Post-deploy
  - Run once: curl -X POST https://vibnai.com/api/admin/migrate \\
      -H "x-admin-secret: \$ADMIN_MIGRATE_SECRET"
  - Existing users get a workspace row on next sign-in.
  - Existing fs_projects keep working (legacy gitea owner + their
    own per-project Coolify Projects); new projects use the
    workspace-scoped path.

Not in this commit (follow-ups)
  - Wiring requireWorkspacePrincipal into the rest of /api/projects/*
    so API keys can drive existing routes
  - HTTP MCP server at /api/mcp (the mcp.json snippet already
    points at the right URL — no client re-setup when it lands)
  - Backfill script to assign legacy fs_projects to a workspace

Made-with: Cursor

app/api/workspaces/route.ts

@@ -0,0 +1,52 @@
+/**
+ * GET /api/workspaces — list workspaces the caller can access
+ *
+ * Auth:
+ *   - NextAuth session: returns the user's owned + member workspaces
+ *   - vibn_sk_... API key: returns just the one workspace the key is bound to
+ */
+
+import { NextResponse } from 'next/server';
+import { authSession } from '@/lib/auth/session-server';
+import { queryOne } from '@/lib/db-postgres';
+import { listWorkspacesForUser } from '@/lib/workspaces';
+import { requireWorkspacePrincipal } from '@/lib/auth/workspace-auth';
+
+export async function GET(request: Request) {
+  // API-key clients are pinned to one workspace
+  if (request.headers.get('authorization')?.toLowerCase().startsWith('bearer vibn_sk_')) {
+    const principal = await requireWorkspacePrincipal(request);
+    if (principal instanceof NextResponse) return principal;
+    return NextResponse.json({ workspaces: [serializeWorkspace(principal.workspace)] });
+  }
+
+  const session = await authSession();
+  if (!session?.user?.email) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const userRow = await queryOne<{ id: string }>(
+    `SELECT id FROM fs_users WHERE data->>'email' = $1 LIMIT 1`,
+    [session.user.email]
+  );
+  if (!userRow) {
+    return NextResponse.json({ workspaces: [] });
+  }
+
+  const list = await listWorkspacesForUser(userRow.id);
+  return NextResponse.json({ workspaces: list.map(serializeWorkspace) });
+}
+
+function serializeWorkspace(w: import('@/lib/workspaces').VibnWorkspace) {
+  return {
+    id: w.id,
+    slug: w.slug,
+    name: w.name,
+    coolifyProjectUuid: w.coolify_project_uuid,
+    giteaOrg: w.gitea_org,
+    provisionStatus: w.provision_status,
+    provisionError: w.provision_error,
+    createdAt: w.created_at,
+    updatedAt: w.updated_at,
+  };
+}