feat: 添加后台登录验证码、记住密码功能，优化媒体资源与前端规范

- 新增后台登录图形验证码功能，完善登录安全防护
- 新增登录rememberMe参数，控制Refresh Token的会话持久化策略
- 实现OSS私有桶媒体URL自动签名，统一处理图片资源的临时访问签名
- 新增素材库数据库表与上传API，规范媒体资源管理流程
- 统一前端UI图标使用@element-plus/icons-vue，重构布局图标组件
- 登录页新增验证码输入、刷新功能，添加账号记忆与记住密码逻辑
- 更新全套文档，补充API契约、技术决策记录与集成流程说明
- 修复多个业务页面的图标展示问题，新增认证流程相关测试用例

WonderQ-Admin/alembic/versions/0034_media_assets.py

@@ -0,0 +1,65 @@
+"""Create the media asset table required by admin uploads."""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy import inspect
+
+
+revision = "0034_media_assets"
+down_revision = "0033_remove_site_versions"
+branch_labels = None
+depends_on = None
+
+DEFAULT_DEPT_ID = "00000000-0000-0000-0000-000000000001"
+
+
+def _table_names() -> set[str]:
+    return set(inspect(op.get_bind()).get_table_names())
+
+
+def upgrade() -> None:
+    if "MediaAsset" in _table_names():
+        return
+
+    op.create_table(
+        "MediaAsset",
+        sa.Column("id", sa.String(), nullable=False),
+        sa.Column("url", sa.String(), nullable=False, unique=True),
+        sa.Column("name", sa.String(), nullable=True),
+        sa.Column("mimeType", sa.String(), nullable=True),
+        sa.Column("sizeBytes", sa.Integer(), nullable=True),
+        sa.Column("group", sa.String(), nullable=True),
+        sa.Column(
+            "deptId",
+            sa.String(),
+            nullable=False,
+            server_default=sa.text(f"'{DEFAULT_DEPT_ID}'"),
+        ),
+        sa.Column("createdById", sa.String(), nullable=True),
+        sa.Column("createdAt", sa.DateTime(), nullable=False),
+        sa.Column("updatedAt", sa.DateTime(), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["deptId"],
+            ["AdminDepartment.id"],
+            name="fk_MediaAsset_deptId",
+            ondelete="RESTRICT",
+        ),
+        sa.ForeignKeyConstraint(
+            ["createdById"],
+            ["AdminUser.id"],
+            name="fk_MediaAsset_createdById",
+            ondelete="SET NULL",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index("ix_MediaAsset_deptId", "MediaAsset", ["deptId"])
+    op.create_index("ix_MediaAsset_createdById", "MediaAsset", ["createdById"])
+
+
+def downgrade() -> None:
+    if "MediaAsset" not in _table_names():
+        return
+
+    op.drop_index("ix_MediaAsset_createdById", table_name="MediaAsset")
+    op.drop_index("ix_MediaAsset_deptId", table_name="MediaAsset")
+    op.drop_table("MediaAsset")