Any seat can be AI-staffed: engineer/designer/analyst atoms + role-aware seat suggestions

The core product thesis made tangible beyond PO/QA:
- Four new golden-tested skill atoms in skills/: code-implementation + bug-diagnosis
  (engineer — output is a reviewable patch/diagnosis artifact; Git write-back stays Phase 2),
  ui-design-spec (designer), requirements-analysis (analyst, also tagged product-owner).
  The catalogue now spans five roles with eight atoms.
- Seat configurator: SuggestedSkills — maps the seat's free-text role name to skill role
  tags and offers the matching set one click ("Use set"). Any role name → staffed with AI.
- AnyRoleSeatTests: an "Backend Engineer" seat (Edison, gated) runs the same pipeline —
  skills assemble, implement-code/Draft parsed, proposal held in the review inbox like any
  governed action. SkillSyncTests updated for the larger catalogue.

Verified: IntegrationTests 44/44, client build green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/TeamUp.IntegrationTests/SkillSyncTests.cs

@@ -49,7 +49,7 @@ public sealed class SkillSyncTests(PostgresFixture postgres) : IClassFixture<Pos
         var syncResponse = await client.PostAsync("/api/skills/sync", content: null);
         Assert.Equal(HttpStatusCode.OK, syncResponse.StatusCode);
         var result = await syncResponse.Content.ReadFromJsonAsync<SyncResult>();
-        Assert.Equal(4, result!.Indexed);
+        Assert.True(result!.Indexed >= 8, $"expected all atoms indexed, got {result.Indexed}");
 
         var productOwner = await client.GetFromJsonAsync<List<SkillSummary>>("/api/skills/?role=product-owner");
         Assert.Contains(productOwner!, s => s.SkillKey == "spec-writing");