feat: implement agent memory with role-to-prompt mapping (Phase 6)

Complete database schema and API implementation for agent memory
aligned with API Platform Engineer role requirements
(agency-agents/engineering/engineering-api-platform-engineer.md)

Schema (migration 004):
  ✓ agent_prompt: template-based prompts with versioning
  ✓ agent_skill: capabilities with effectiveness tracking
  ✓ agent_decision: reasoning and outcome recording
  ✓ role_prompt_mapping: maps roles (e.g., api-platform-engineer) to prompts
  ✓ agent_metrics: performance tracking per agent
  ✓ prompt_usage_log: detailed invocation tracking
  ✓ agent_registry: agent lifecycle management

API Endpoints (contract-first, backward-compatible):
  POST   /memory/agents/{project_id}/prompts
  POST   /memory/agents/{project_id}/roles
  GET    /memory/agents/{project_id}/roles/{role_name}/prompts

Handlers:
  ✓ create_prompt_handler: persists to agent_prompt table
  ✓ map_role_to_prompt_handler: role → prompt mapping with priority
  ✓ get_role_prompts_handler: retrieves prompts by role

Repository Layer (mem-store/src/agent_repo.rs):
  ✓ AgentRepository with full CRUD operations
  ✓ Prompt usage tracking and statistics
  ✓ Role-to-prompt mapping with priority ordering
  ✓ Metrics persistence for observability

Tekton Pipeline:
  ✓ agent-memory-migration-task: applies schema migration
  ✓ verify-indexes: validates all indexes created
  ✓ verify-schemas: validates table structure
  ✓ integration into poimen-ci pipeline

Integration Tests (tests/agent_memory_api_platform_engineer.rs):
  ✓ Contract-first API specification validation
  ✓ Backward compatibility rule enforcement
  ✓ Rate limiting communication (X-RateLimit-* headers)
  ✓ Error response consistency (stable codes + request IDs)
  ✓ Deprecation lifecycle (announce → signal → runway → sunset)
  ✓ Idempotency and retry safety
  ✓ API Platform Engineer role requirements
  ✓ Agent prompt templates for contract review, compatibility check, SDK generation

All tests validate against agency-agents API Platform Engineer specification:
  - Contract-first: OpenAPI spec before code
  - No breaking changes without versioning
  - Consistent error handling (RFC 9457 problem details)
  - Rate limits communicated not enforced
  - SDKs + docs generated from spec
  - Idempotency via Idempotency-Key header
  - Deprecation with runway (6-12+ months)

Ready to deploy: run Tekton PipelineRun to apply migrations + test

migrations/004_agent_memory_schema.sql

@@ -0,0 +1,142 @@
+-- Agent Memory Schema (Phase 6)
+-- Stores agent prompts, skills, and decisions with role-to-prompt mapping
+-- Follows API Platform Engineer contract-first design (agency-agents role)
+
+CREATE TABLE IF NOT EXISTS agent_prompt (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  name VARCHAR(512) NOT NULL,
+  template TEXT NOT NULL,
+  target_model VARCHAR(128),
+  task_category VARCHAR(128) NOT NULL,
+  usage_count BIGINT DEFAULT 0,
+  avg_quality FLOAT DEFAULT 0.0,
+  last_used TIMESTAMP WITH TIME ZONE,
+  active BOOLEAN DEFAULT true,
+  version INTEGER DEFAULT 1,
+  tags TEXT[] DEFAULT '{}',
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  UNIQUE(project_id, name, version)
+);
+
+CREATE INDEX idx_agent_prompt_project_active ON agent_prompt(project_id, active);
+CREATE INDEX idx_agent_prompt_task_category ON agent_prompt(task_category);
+CREATE INDEX idx_agent_prompt_tags ON agent_prompt USING GIN(tags);
+
+-- Agent Skill: linked capabilities with effectiveness tracking
+CREATE TABLE IF NOT EXISTS agent_skill (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  agent_id VARCHAR(255) NOT NULL,
+  name VARCHAR(512) NOT NULL,
+  description TEXT NOT NULL,
+  trigger_patterns TEXT[] DEFAULT '{}',
+  success_rate FLOAT DEFAULT 0.0,
+  invocation_count BIGINT DEFAULT 0,
+  avg_latency_ms BIGINT DEFAULT 0,
+  linked_prompts UUID[] DEFAULT '{}',
+  enabled BOOLEAN DEFAULT true,
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  UNIQUE(project_id, agent_id, name)
+);
+
+CREATE INDEX idx_agent_skill_agent ON agent_skill(project_id, agent_id);
+CREATE INDEX idx_agent_skill_enabled ON agent_skill(enabled);
+CREATE INDEX idx_agent_skill_linked_prompts ON agent_skill USING GIN(linked_prompts);
+
+-- Agent Decision: reasoning and outcome tracking
+CREATE TABLE IF NOT EXISTS agent_decision (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  agent_id VARCHAR(255) NOT NULL,
+  action VARCHAR(512) NOT NULL,
+  reasoning TEXT NOT NULL,
+  alternatives TEXT[] DEFAULT '{}',
+  confidence FLOAT DEFAULT 0.0,
+  context_entities UUID[] DEFAULT '{}',
+  tool VARCHAR(255),
+  task VARCHAR(255),
+  outcome_success BOOLEAN,
+  outcome_quality FLOAT,
+  outcome_feedback TEXT,
+  outcome_recorded_at TIMESTAMP WITH TIME ZONE,
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+CREATE INDEX idx_agent_decision_agent ON agent_decision(project_id, agent_id);
+CREATE INDEX idx_agent_decision_action ON agent_decision(action);
+CREATE INDEX idx_agent_decision_context ON agent_decision USING GIN(context_entities);
+
+-- Agent Registration: lifecycle management
+CREATE TABLE IF NOT EXISTS agent_registry (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  agent_id VARCHAR(255) NOT NULL,
+  capabilities TEXT[] NOT NULL,
+  webhook_url VARCHAR(2048),
+  rate_limit INTEGER DEFAULT 1000,
+  metadata JSONB DEFAULT '{}',
+  status VARCHAR(32) DEFAULT 'active',
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  UNIQUE(project_id, agent_id)
+);
+
+CREATE INDEX idx_agent_registry_project ON agent_registry(project_id);
+CREATE INDEX idx_agent_registry_status ON agent_registry(status);
+
+-- Role-to-Prompt Mapping: maps agent roles to prompt templates
+CREATE TABLE IF NOT EXISTS role_prompt_mapping (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  role_name VARCHAR(255) NOT NULL,
+  prompt_id UUID NOT NULL REFERENCES agent_prompt(id) ON DELETE CASCADE,
+  priority INTEGER DEFAULT 0,
+  active BOOLEAN DEFAULT true,
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  UNIQUE(project_id, role_name, prompt_id),
+  FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE
+);
+
+CREATE INDEX idx_role_prompt_mapping_role ON role_prompt_mapping(project_id, role_name, active);
+CREATE INDEX idx_role_prompt_mapping_prompt ON role_prompt_mapping(prompt_id);
+
+-- Agent Metrics: performance tracking
+CREATE TABLE IF NOT EXISTS agent_metrics (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  agent_id VARCHAR(255) NOT NULL,
+  requests_total BIGINT DEFAULT 0,
+  requests_success BIGINT DEFAULT 0,
+  requests_failed BIGINT DEFAULT 0,
+  average_latency_ms FLOAT DEFAULT 0.0,
+  p95_latency_ms FLOAT DEFAULT 0.0,
+  p99_latency_ms FLOAT DEFAULT 0.0,
+  error_rate FLOAT DEFAULT 0.0,
+  recorded_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+  UNIQUE(project_id, agent_id, DATE(recorded_at))
+);
+
+CREATE INDEX idx_agent_metrics_agent ON agent_metrics(project_id, agent_id, recorded_at DESC);
+
+-- Prompt Usage Log: detailed invocation tracking
+CREATE TABLE IF NOT EXISTS prompt_usage_log (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id VARCHAR(255) NOT NULL,
+  prompt_id UUID NOT NULL REFERENCES agent_prompt(id) ON DELETE CASCADE,
+  agent_id VARCHAR(255),
+  model_used VARCHAR(128),
+  input_tokens INTEGER,
+  output_tokens INTEGER,
+  quality_score FLOAT,
+  duration_ms BIGINT,
+  error_message TEXT,
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+CREATE INDEX idx_prompt_usage_log_prompt ON prompt_usage_log(prompt_id, created_at DESC);
+CREATE INDEX idx_prompt_usage_log_agent ON prompt_usage_log(agent_id, created_at DESC);