feat(inception): UI — New-project modal step 2, InceptionCard on the project page, Rules tab shows excluded always-on rulebooks; REST exclusion routes (#2883, milestone 297 step 5)

- components/InceptionCard.vue: the one form, two homes — mode="create" in
  the New-project modal's second step (emits the choices; the create carries
  `inception`), mode="decide" on ProjectView for the owner of an undecided
  project (loads that project's defaults, records the decision). Always-on
  rulebooks listed checked (uncheck = exclude), others unchecked (check =
  subscribe), design system select, seed-Systems toggle (disabled once the
  project has Systems). Tokens only; modal canon (#2855); .btn-* canon.
- ProjectView: the card while undecided, one "Inheritance decided <date> via
  … · …" line after; onDecided refreshes the project.
- ProjectRulesTab: "Excluded always-on rulebooks" section with include-back.
- api/inception.ts (types, fetchInceptionDefaults, decideInception);
  api/rulebooks.ts: ApplicableRules.excluded_always_on, exclude/include
  wrappers; REST POST/DELETE /api/projects/<id>/exclusions/rulebooks/<rb>.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/ProjectView.vue

@@ -11,6 +11,9 @@ import ShareDialog from "@/components/ShareDialog.vue";
 import ProjectDesignTab from "@/components/ProjectDesignTab.vue";
 import ProjectRulesTab from "@/components/rules/ProjectRulesTab.vue";
 import SystemsSection from "@/components/SystemsSection.vue";
+import InceptionCard from "@/components/InceptionCard.vue";
+import { fmtDate } from "@/utils/dateFormat";
+import type { InceptionDecision, InceptionRecord } from "@/api/inception";
 import {
   fetchDesignSystems,
   setProjectDesignSystem,
@@ -50,6 +53,7 @@ interface Project {
   color: string | null;
   design_system_id: number | null;
   forge_connection_id: number | null;
+  inception?: InceptionRecord | null;
   permission?: string;
   created_at: string;
   updated_at: string;
@@ -75,6 +79,12 @@ interface NoteItem {
 const route = useRoute();
 const router = useRouter();
 const toast = useToastStore();
+
+function onInceptionDecided(decision: InceptionDecision) {
+  if (project.value) project.value.inception = decision.inception;
+  toast.show("Inheritance recorded");
+  void loadProject();
+}
 const tasksStore = useTasksStore();
 
 const project = ref<Project | null>(null);
@@ -695,6 +705,26 @@ async function confirmDelete() {
         </p>
       </div>
 
+      <!-- Inception (milestone 297): the owner of an undecided project is asked
+           what it inherits; once recorded, one line says what was decided. -->
+      <InceptionCard
+        v-if="project.inception == null && isProjectOwner"
+        mode="decide"
+        :project-id="projectId"
+        @decided="onInceptionDecided"
+      />
+      <p v-else-if="project.inception" class="inception-line">
+        Inheritance decided {{ fmtDate(project.inception.decided_at) }} via {{ project.inception.via }}
+        <template v-if="project.inception.choices.exclude_always_on_rulebooks.length">
+          · excludes {{ project.inception.choices.exclude_always_on_rulebooks.length }} always-on rulebook(s)
+        </template>
+        <template v-if="project.inception.choices.subscribe_rulebooks.length">
+          · subscribes {{ project.inception.choices.subscribe_rulebooks.length }}
+        </template>
+        · design system {{ project.inception.choices.design_system_id ? "#" + project.inception.choices.design_system_id : "none" }}
+        <template v-if="project.inception.choices.seed_systems"> · Systems seeded</template>
+      </p>
+
       <!-- Summary stat chips -->
       <div v-if="project.summary" class="summary-stats">
         <div class="stat-chip stat-todo">
@@ -1197,6 +1227,7 @@ async function confirmDelete() {
   min-width: 200px;
 }
 
+.inception-line { margin: 0 0 1rem; color: var(--fs-text-secondary); font-size: 0.85rem; }
 .project-title-input {
   flex: 1;
   font-size: 1.75rem;