feat: 회고 시스템 Phase 1 캡처 파이프라인

chat_bridge에 회고 채널 텍스트 폴링 + n8n 포워딩 추가.
n8n 워크플로우(8노드): Webhook → Validate → Qwen 분류 → PostgreSQL INSERT → Chat 확인.
retrospect 스키마 + 3 테이블 (entries, reviews, patterns).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

init/migrate-v6.sql

@@ -0,0 +1,50 @@
+-- migrate-v6.sql: 회고 시스템 (retrospect) 스키마 + 테이블
+-- 실행: docker exec -i bot-postgres psql -U bot -d chatbot < init/migrate-v6.sql
+
+CREATE SCHEMA IF NOT EXISTS retrospect;
+
+CREATE TABLE IF NOT EXISTS retrospect.entries (
+    id              BIGSERIAL PRIMARY KEY,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    raw_text        TEXT NOT NULL,
+    domain          VARCHAR(20) NOT NULL,       -- work | health | finance
+    entry_type      VARCHAR(20) NOT NULL,       -- event | reflection | regret | log
+    sentiment       VARCHAR(10) NOT NULL,       -- positive | neutral | negative
+    tags            TEXT[] DEFAULT '{}',
+    confidence      REAL DEFAULT 0.0,
+    source          VARCHAR(20) DEFAULT 'chat',
+    reviewed        BOOLEAN DEFAULT FALSE,
+    source_post_id  INTEGER,
+    username        VARCHAR(100)
+);
+
+CREATE INDEX IF NOT EXISTS idx_entries_created ON retrospect.entries (created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_entries_domain ON retrospect.entries (domain);
+CREATE INDEX IF NOT EXISTS idx_entries_type ON retrospect.entries (entry_type);
+CREATE INDEX IF NOT EXISTS idx_entries_reviewed ON retrospect.entries (reviewed) WHERE NOT reviewed;
+CREATE INDEX IF NOT EXISTS idx_entries_tags ON retrospect.entries USING GIN(tags);
+-- 중복 방지: chat_bridge 재시작 시 같은 post 재처리 방지
+CREATE UNIQUE INDEX IF NOT EXISTS idx_entries_post_id ON retrospect.entries (source_post_id)
+    WHERE source_post_id IS NOT NULL;
+
+CREATE TABLE IF NOT EXISTS retrospect.reviews (
+    id              BIGSERIAL PRIMARY KEY,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    review_type     VARCHAR(10) NOT NULL,       -- daily | weekly | monthly
+    period_start    DATE NOT NULL,
+    period_end      DATE NOT NULL,
+    content         TEXT NOT NULL,
+    entry_ids       BIGINT[] DEFAULT '{}',
+    model_used      VARCHAR(50) NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS retrospect.patterns (
+    id              BIGSERIAL PRIMARY KEY,
+    discovered_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    domain          VARCHAR(20) NOT NULL,
+    pattern_type    VARCHAR(20) NOT NULL,       -- recurring_mistake | habit | correlation | improvement
+    description     TEXT NOT NULL,
+    occurrences     INTEGER DEFAULT 1,
+    last_seen       DATE NOT NULL,
+    status          VARCHAR(20) DEFAULT 'active'
+);