fix(migration): split 102 ask_events into single-statement files

asyncpg cannot insert multiple commands into a prepared statement.
102 = CREATE TABLE only, 103 = CREATE INDEX only.

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

migrations/102_ask_events.sql

@@ -1,26 +1,18 @@
--- Phase 3.5a: /ask 호출 관측 테이블
--- refusal rate 측정, 지표 3 분리 (full/partial/insufficient), defense layer 디버깅
-
 CREATE TABLE IF NOT EXISTS ask_events (
     id BIGSERIAL PRIMARY KEY,
     query TEXT NOT NULL,
     user_id BIGINT REFERENCES users(id),
-    completeness TEXT,               -- full / partial / insufficient
+    completeness TEXT,
     synthesis_status TEXT,
     confidence TEXT,
     refused BOOLEAN DEFAULT false,
-    classifier_verdict TEXT,          -- sufficient / insufficient / null (skipped)
+    classifier_verdict TEXT,
     max_rerank_score REAL,
     aggregate_score REAL,
     hallucination_flags JSONB DEFAULT '[]',
     evidence_count INT,
     citation_count INT,
-    defense_layers JSONB,            -- per-layer flag snapshot (score_gate, classifier, grounding)
+    defense_layers JSONB,
     total_ms INT,
     created_at TIMESTAMPTZ DEFAULT now()
-);
-
-CREATE INDEX IF NOT EXISTS idx_ask_events_created ON ask_events(created_at);
-CREATE INDEX IF NOT EXISTS idx_ask_events_completeness ON ask_events(completeness);
-
-INSERT INTO schema_migrations (version) VALUES (102);
+)