Rework single-agent workflows; add write-tests; remove comparative-plan

- claude-agent → standard-agent (complexity≥8, spec_adherence≥9 → Sonnet-class)
- smart-agent: complexity≥9 → Opus; documents MiniMax not in registry
- functional-agent: labels=[airouter], cost_efficiency≥9 → Qwen3.6
- write-tests: two-node DAG (write_tests → review_coverage), spec-driven
  test authoring with coverage gap report in JSON
- Remove comparative-plan (superseded by tdd-impl audit pattern)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

workflows/functional-agent.yaml

@@ -0,0 +1,49 @@
+name: functional-agent
+version: 1
+description: >
+  Cost-efficient single-agent workflow via Airouter (Qwen3.6). Routes exclusively to
+  the airouter dispatcher (labels: [airouter], cost_efficiency ≥ 9). Use for narrow,
+  well-scoped tasks where throughput and cost matter — parallel subsystem work,
+  bulk fixes, or tasks with explicit instructions.
+
+  Hard cap: 3 concurrent airouter tasks. No web search available in container.
+  Keep prompts directive and single-file/single-concern scoped for best results.
+
+params:
+  required:
+    task_description:
+      type: string
+      description: "Task prompt for the agent"
+    project_id:
+      type: string
+      description: "Project identifier for task grouping"
+    repo_url:
+      type: string
+      description: "Git repo URL for the agent to clone"
+    agent_repo_url:
+      type: string
+      description: "Agent repo URL for branch-per-task persistence"
+  optional:
+    harness:
+      type: string
+      default: "code-airouter-repo/v1"
+      description: "Harness to use. Override to change context/credentials (default: code-airouter-repo/v1)"
+    space_id:
+      type: string
+      default: "default"
+      description: "Space identifier"
+
+nodes:
+  agent:
+    name: "agent"
+    prompt: "{{ task_description }}"
+    harness: "{{ harness }}"
+    requirements:
+      labels: [airouter]
+      min_scores:
+        cost_efficiency: 9
+    on_success:
+      - type: commit_pr
+        params:
+          repo_url: "{{ repo_url }}"
+          agent_repo_url: "{{ agent_repo_url }}"