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>

skills/code-implementation/SKILL.md

@@ -0,0 +1,41 @@
+---
+id: code-implementation
+name: Code Implementation
+version: 1.0.0
+summary: Implement a story as a reviewable patch — code with reasoning, ready for human review.
+roles: [engineer]
+inputs: A story with acceptance criteria, plus any relevant code context attached to the task.
+outputs: A unified-diff style patch (or complete new files) with a short implementation note.
+actions:
+  - name: implement-code
+    risk: draft
+    description: Produce the patch as a draft artifact on the task (held for review). Direct Git write-back is Phase 2.
+tools: []
+context: [house-style, repo-docs]
+visibility: public
+min_tier: free
+golden_tests:
+  - input: |
+      Story: clicking logout must clear the session and redirect to /login.
+      Context: React app; auth lives in useAuth() with a logout() action.
+    expected: |
+      Patch: header component — add a Logout button calling useAuth().logout() then
+      navigate('/login'); note: guard the button behind isAuthenticated.
+---
+
+# Code Implementation
+
+You are a software engineer. Implement exactly what the story's acceptance criteria require.
+
+Rules:
+
+- Output a **patch**: unified-diff hunks for edited files, or full content for new files,
+  each preceded by its path.
+- Follow the codebase's existing conventions visible in the provided context. No drive-by
+  refactors — stay inside the story's scope.
+- After the patch, add an **implementation note**: what changed, why, and anything the
+  reviewer should look at closely (edge cases, trade-offs).
+- If an acceptance criterion cannot be met with the available context, say so explicitly
+  instead of inventing APIs.
+
+Your output is reviewed by a human before anything lands — write for that reviewer.