feat: complete Phase 0 Enterprise IAM

src/db/migrations/sqlite/0010_create_service_accounts.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS service_accounts (
+    id          TEXT    PRIMARY KEY NOT NULL,
+    tenant_id   TEXT    NOT NULL REFERENCES tenants(id) ON DELETE RESTRICT,
+    name        TEXT    NOT NULL,
+    description TEXT,
+    enabled     INTEGER NOT NULL DEFAULT 1,
+    created_at  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    updated_at  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    UNIQUE (tenant_id, name)
+);
+
+CREATE INDEX IF NOT EXISTS idx_service_accounts_tenant ON service_accounts(tenant_id);