feat(core): update backend coordinator, docgov lease, squad workflow and web governance integration

deploy/postgres/context_init.sql

@@ -162,7 +162,8 @@ CREATE TABLE IF NOT EXISTS context_memory_chunks (
 
 CREATE INDEX IF NOT EXISTS idx_mem_chunks_domain_proj ON context_memory_chunks(domain, project_id, created_at DESC);
 CREATE INDEX IF NOT EXISTS idx_mem_chunks_user ON context_memory_chunks(user_id, domain);
-CREATE INDEX IF NOT EXISTS idx_mem_chunks_hash ON context_memory_chunks(chunk_hash);
+-- chunk_hash 必须唯一：IndexApprovedDocument 使用 ON CONFLICT (chunk_hash)
+CREATE UNIQUE INDEX IF NOT EXISTS uq_mem_chunks_hash ON context_memory_chunks(chunk_hash);
 CREATE INDEX IF NOT EXISTS idx_mem_chunks_tsv ON context_memory_chunks USING gin (tsv);
 CREATE INDEX IF NOT EXISTS idx_mem_chunks_vec ON context_memory_chunks USING hnsw (embedding vector_cosine_ops);
 
@@ -210,6 +211,14 @@ CREATE TABLE IF NOT EXISTS document_records (
 
     -- 可配置项 (Config JSONB)
     config                  JSONB NOT NULL DEFAULT '{"reject_rollback_to": "drafting", "allow_approver_to_reviewer": true}'::jsonb,
+
+    -- 编辑租约 (运行时互斥，正交于 is_locked)
+    lease_holder_type       TEXT NOT NULL DEFAULT '',          -- squad | human | ''
+    lease_holder_id         TEXT NOT NULL DEFAULT '',          -- run_id / user_id
+    lease_work_dir          TEXT NOT NULL DEFAULT '',
+    lease_expires_at        TIMESTAMPTZ,
+    lease_heartbeat_at      TIMESTAMPTZ,
+
     created_at              TIMESTAMPTZ NOT NULL DEFAULT now(),
     updated_at              TIMESTAMPTZ NOT NULL DEFAULT now()
 );