feat(rules)!: retire rulebook subscriptions and per-project suppressions (#4052)

A rule's home is its scope now: a rule in a rulebook topic is global, a rule on
a project applies to that project, and retrieval reads that directly (#4074).
A subscription had stopped changing anything a session received; a suppression
muted rules from a subscription. Operator, 2026-09-15: "we have global and
project scoped rules, we don't need the subscriptions now."

What goes, whole (rule 22):
- Migration 0101 drops project_rulebook_subscriptions, project_rule_suppressions
  and project_topic_suppressions, and strips subscribe_rulebooks (and 394's
  leftover exclude_always_on_rulebooks) from stored inception choices.
- Service, MCP and REST: subscribe/unsubscribe and the four suppress/unsuppress
  operations. The Subscribers checklist, the subscribe chips, the skip buttons
  and the Suppressed section in the rules UI.
- Inception asks two questions (design system, seed Systems). create_project and
  decide_project_inception lose subscribe_rulebooks.
- Backup v15 stops exporting the three sections; older archives still restore,
  the keys simply unread. Trash no longer hard-deletes suppression rows.

What changes meaning:
- get_applicable_rules is a project's LISTING: its own rules, plus the global
  rules tagged to an area it works in. Untagged global rules apply everywhere
  and arrive by retrieval, so they are not listed. A co_surfaces partner on a
  different project is not dragged in.
- list_rules(project_id) lists that project's own rules.
- rules_payload drops subscribed_rulebooks and suppressed_*; the handshake's
  brief form is project_rules alone.
- using-scribe's "Where a new rule goes" and inception sections, tool
  docstrings and docs say global vs project. Plugin 2026.09.15.1620.

Milestone 414 step 2.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

frontend/src/components/rules/RulebookDetailPane.vue

@@ -1,12 +1,11 @@
 <script setup lang="ts">
-import { ref, onMounted, watch } from "vue";
+import { ref } from "vue";
 import { useRulebooksStore } from "@/stores/rulebooks";
-import { apiGet } from "@/api/client";
-import {
-  subscribeProject, unsubscribeProject, getProjectApplicableRules,
-} from "@/api/rulebooks";
 import type { RulebookTopic } from "@/api/rulebooks";
 
+// A rulebook's rules are global — they apply to every project — so this pane
+// lists topics and nothing else. It carried a "Subscribers" checklist of
+// projects until milestone 414 retired subscriptions.
 const props = defineProps<{
   rulebookId: number;
   topics: RulebookTopic[];
@@ -18,42 +17,6 @@ const store = useRulebooksStore();
 const isCreating = ref(false);
 const newTitle = ref("");
 
-
-interface ProjectLite { id: number; title: string }
-const projects = ref<ProjectLite[]>([]);
-// Map<project_id, Set<rulebook_id>>
-const subscribedRulebookIds = ref<Map<number, Set<number>>>(new Map());
-
-async function loadProjects() {
-  const data = await apiGet<{ projects: ProjectLite[] }>("/api/projects");
-  projects.value = data.projects;
-  for (const p of projects.value) {
-    const result = await getProjectApplicableRules(p.id);
-    subscribedRulebookIds.value.set(
-      p.id,
-      new Set(result.subscribed_rulebooks.map((rb) => rb.id)),
-    );
-  }
-}
-
-function isSubscribed(projectId: number): boolean {
-  return subscribedRulebookIds.value.get(projectId)?.has(props.rulebookId) ?? false;
-}
-
-async function toggleSubscription(projectId: number, checked: boolean) {
-  if (checked) {
-    await subscribeProject(projectId, props.rulebookId);
-    const set = subscribedRulebookIds.value.get(projectId) || new Set<number>();
-    set.add(props.rulebookId);
-    subscribedRulebookIds.value.set(projectId, set);
-  } else {
-    await unsubscribeProject(projectId, props.rulebookId);
-    subscribedRulebookIds.value.get(projectId)?.delete(props.rulebookId);
-  }
-  // trigger reactivity on Map mutation
-  subscribedRulebookIds.value = new Map(subscribedRulebookIds.value);
-}
-
 async function submitNew() {
   const title = newTitle.value.trim();
   if (!title) return;
@@ -63,8 +26,6 @@ async function submitNew() {
   emit("select-topic", topic.id);
 }
 
-onMounted(loadProjects);
-watch(() => props.rulebookId, () => {/* re-render of isSubscribed from existing map */});
 </script>
 
 <template>
@@ -92,21 +53,6 @@ watch(() => props.rulebookId, () => {/* re-render of isSubscribed from existing
         </div>
       </form>
     </div>
-    <div class="subscriptions">
-      <h3>Subscribers</h3>
-      <ul class="sub-list">
-        <li v-for="p in projects" :key="p.id">
-          <label>
-            <input
-              type="checkbox"
-              :checked="isSubscribed(p.id)"
-              @change="toggleSubscription(p.id, ($event.target as HTMLInputElement).checked)"
-            />
-            {{ p.title }}
-          </label>
-        </li>
-      </ul>
-    </div>
   </section>
 </template>
 
@@ -117,24 +63,13 @@ ul { list-style: none; padding: 0; margin: 1rem 0; }
 li { padding: 0.5rem; cursor: pointer; border-radius: 6px; }
 li.active { background: var(--fs-accent-soft); }
 li:hover { background: var(--fs-surface-hover); }
-/* `.new-topic` and `.sub-list` are deliberately bare (#2444). The first wraps a
-   button-or-form whose children style themselves; the second is a `<ul>`, and
-   the bare `ul` rule above already gives it list-style, padding and margin —
-   a base a class-name check cannot see, since it comes from an element
-   selector. Both namespace descendant rules and assume nothing about layout. */
+/* `.new-topic` is deliberately bare (#2444): it wraps a button-or-form whose
+   children style themselves, and namespaces the descendant rule below. */
 .new-topic input {
   width: 100%; margin-bottom: 0.5rem;
   background: var(--fs-surface-page); color: inherit;
   border: 1px solid var(--fs-border-color); border-radius: 6px;
   padding: 0.5rem;
 }
-.subscriptions {
-  margin-top: 2rem;
-  border-top: 1px solid var(--fs-border-color);
-  padding-top: 1rem;
-}
-.subscriptions h3 { font-size: 0.9em; opacity: 0.7; text-transform: uppercase; letter-spacing: 0.05em; }
-.sub-list li { cursor: default; }
-.sub-list label { display: flex; gap: 0.5rem; align-items: center; cursor: pointer; }
 button { cursor: pointer; }
 </style>