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- Remove comparative-plan (superseded by tdd-impl audit pattern)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/standard-agent.yaml

@@ -0,0 +1,45 @@
+name: standard-agent
+version: 1
+description: >
+  Standard single-agent workflow. Routes to a capable, balanced model
+  (complexity ≥ 8, spec_adherence ≥ 9 — currently selects from Sonnet-class models).
+  Default for most implementation tasks where quality and cost are balanced.
+
+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-sonnet-repo/v1"
+      description: "Harness to use. Override to change context/credentials (default: code-sonnet-repo/v1)"
+    space_id:
+      type: string
+      default: "default"
+      description: "Space identifier"
+
+nodes:
+  agent:
+    name: "agent"
+    prompt: "{{ task_description }}"
+    harness: "{{ harness }}"
+    requirements:
+      min_scores:
+        complexity: 8
+        spec_adherence: 9
+    on_success:
+      - type: commit_pr
+        params:
+          repo_url: "{{ repo_url }}"
+          agent_repo_url: "{{ agent_repo_url }}"