feat(db): add decisions sync script and schema tables

Add decisions_sync.py that parses decisions/*.md markdown headings,
extracts metadata (type, domain, status, round, date), and upserts
into SQLite. Two-pass approach: decisions first, then cross-references
to avoid FK violations on forward references.

Schema adds decisions table (52 rows) and decision_refs table (29 rows)
with cascading deletes. Makefile gains decisions-sync, decisions-coverage,
decisions-active, and decisions-orphan targets. Sync runs as part of
make setup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

db/schema.sql

@@ -59,3 +59,35 @@ CREATE INDEX IF NOT EXISTS idx_tickets_sprint ON tickets(sprint_id);
 CREATE INDEX IF NOT EXISTS idx_tickets_assigned ON tickets(assigned_to);
 CREATE INDEX IF NOT EXISTS idx_tickets_decision ON tickets(decision_ref);
 CREATE INDEX IF NOT EXISTS idx_history_ticket ON ticket_history(ticket_id);
+
+-- ---------------------------------------------------------------------------
+-- Decision Sync Tables
+-- Populated by: python3 db/connectors/decisions_sync.py
+-- Source: decisions/*.md domain files
+-- ---------------------------------------------------------------------------
+
+CREATE TABLE IF NOT EXISTS decisions (
+    id TEXT PRIMARY KEY,
+    type TEXT NOT NULL CHECK(type IN ('confirmed', 'question', 'rejected')),
+    domain TEXT NOT NULL,
+    title TEXT NOT NULL,
+    status TEXT DEFAULT 'active' CHECK(status IN ('active', 'superseded', 'resolved', 'open')),
+    round INTEGER,
+    date TEXT,
+    file_path TEXT NOT NULL,
+    synced_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS decision_refs (
+    source_id TEXT NOT NULL REFERENCES decisions(id) ON DELETE CASCADE,
+    target_id TEXT NOT NULL REFERENCES decisions(id) ON DELETE CASCADE,
+    ref_type TEXT NOT NULL CHECK(ref_type IN ('supersedes', 'references', 'resolves', 'depends_on')),
+    note TEXT,
+    PRIMARY KEY (source_id, target_id, ref_type)
+);
+
+CREATE INDEX IF NOT EXISTS idx_decisions_type ON decisions(type);
+CREATE INDEX IF NOT EXISTS idx_decisions_domain ON decisions(domain);
+CREATE INDEX IF NOT EXISTS idx_decisions_status ON decisions(status);
+CREATE INDEX IF NOT EXISTS idx_decision_refs_source ON decision_refs(source_id);
+CREATE INDEX IF NOT EXISTS idx_decision_refs_target ON decision_refs(target_id);