feat(billing): enforce image generation quota with admin API and user display

Add period_images_bonus and ledger tracking, gate image_make on remaining quota,
expose admin image-quota routes, show remaining image quota in the balance popover,
and document that admin UI must live in memind_adm (5174) not ops.

Co-authored-by: Cursor <cursoragent@cursor.com>

schema.sql

@@ -1181,6 +1181,7 @@ CREATE TABLE IF NOT EXISTS h5_subscriptions (
   period_tokens_used BIGINT NOT NULL DEFAULT 0,
   period_images_limit INT NOT NULL DEFAULT 0,
   period_images_used INT NOT NULL DEFAULT 0,
+  period_images_bonus INT NOT NULL DEFAULT 0,
   period_start BIGINT NOT NULL,
   period_end BIGINT NOT NULL,
   expires_at BIGINT NOT NULL,
@@ -1195,6 +1196,21 @@ CREATE TABLE IF NOT EXISTS h5_subscriptions (
   CONSTRAINT fk_h5_sub_user FOREIGN KEY (user_id) REFERENCES h5_users(id) ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+CREATE TABLE IF NOT EXISTS h5_image_quota_ledger (
+  id CHAR(36) PRIMARY KEY,
+  user_id CHAR(36) NOT NULL,
+  delta INT NOT NULL,
+  balance_after INT NULL,
+  reason ENUM('admin_grant', 'admin_adjust', 'consume', 'period_reset', 'plan_change') NOT NULL,
+  ref_id VARCHAR(128) NULL,
+  operator_id CHAR(36) NULL,
+  note VARCHAR(512) NULL,
+  created_at BIGINT NOT NULL,
+  KEY idx_h5_image_quota_user_created (user_id, created_at),
+  KEY idx_h5_image_quota_ref (user_id, ref_id),
+  CONSTRAINT fk_h5_image_quota_user FOREIGN KEY (user_id) REFERENCES h5_users(id) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
 CREATE TABLE IF NOT EXISTS h5_blocked_words (
   id CHAR(36) PRIMARY KEY,
   word VARCHAR(200) NOT NULL,