feat(pipeline): G-pre1/2/3 — Object Clustering + Master Controls + API

G-pre1: 144k objects clustered into 7,466 groups via Mini-Batch K-Means
  on bge-m3 embeddings. Two-stage: k=5000 base + sub-cluster groups >50.
G-pre2: 5,114 Master Controls from lifecycle phase chains
  (define→implement→test→monitor), linking 172,504 atomic controls.
G-pre3: REST API for Master Controls
  GET /v1/master-controls (list, search, filter)
  GET /v1/master-controls/stats
  GET /v1/master-controls/{mc_id} (detail with phase-controls)

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

control-pipeline/migrations/004_object_groups.sql

@@ -0,0 +1,18 @@
+-- Migration 004: Object Groups (G-pre1)
+-- Schema: compliance
+-- Run: ssh macmini "docker exec -i bp-core-postgres psql -U breakpilot -d breakpilot_db" < control-pipeline/migrations/004_object_groups.sql
+
+SET search_path TO compliance, public;
+
+CREATE TABLE IF NOT EXISTS object_groups (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    group_id INTEGER NOT NULL,
+    canonical_name VARCHAR(200) NOT NULL,
+    member_count INTEGER DEFAULT 0,
+    members JSONB DEFAULT '[]',
+    top_controls_count INTEGER DEFAULT 0,
+    created_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_object_groups_group_id ON object_groups(group_id);
+CREATE INDEX IF NOT EXISTS idx_object_groups_canonical ON object_groups(canonical_name);