feat(subscriptions): 按 MP 收敛订阅默认值与表单

- 定时主动搜索默认关(DEFAULT_SEARCH_INTERVAL_HOURS = 0),新建 / 手动照常各搜一次,之后靠 RSS 与站点快照
- 多版本自动补全系统缺省改为关
- 表单:基础页 = 作品与范围、下载、洗版;收录版本、优先级、自动补全折叠到进阶页「多版本」
- 对照文档 §7.3 记录落实范围

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/server/test/subscriptions/overview-domain.test.ts

@@ -86,7 +86,7 @@ describe("coverageRow", () => {
 });
 
 describe("自动补全开关与补全预算", () => {
-  it("订阅显式值优先;inherit 取规则链上最后一个设了 autoFill 的组;都没设为开", () => {
+  it("订阅显式值优先;inherit 取规则链上最后一个设了 autoFill 的组;都没设为关(MP 没有多版本补全)", () => {
     expect(resolveAutoFill("off", [{ id: "g", autoFill: true }])).toMatchObject({
       enabled: false,
       source: "subscription",
@@ -99,7 +99,7 @@ describe("自动补全开关与补全预算", () => {
       ]),
     ).toEqual({ enabled: false, mode: "inherit", source: "rule_group", ruleGroupId: "b" });
     expect(resolveAutoFill(undefined, [{ id: "a", autoFill: null }])).toEqual({
-      enabled: true,
+      enabled: false,
       mode: "inherit",
       source: "default",
     });