§22 M3 frontend: /p/<project>/ routing, runtime branding, directory, 308s (v0.35.0)

Implements the M3-frontend slice of the §22 multi-project track, per
docs/superpowers/specs/2026-06-03-m3-frontend-design.md (design merged in
#10). Completes the runtime-config cut 0.33.0 (M3-backend Plan A) began.

Frontend:
- DeploymentProvider boots GET /api/deployment → {name, tagline,
  defaultProjectId, projects}; brandTitle() neutral 'RFC' pre-fetch fallback.
- /p/:projectId/* routing with generic /e/<slug> segment. ProjectLayout
  fetches /api/projects/:id, applies per-project theme (reset on switch),
  provides ProjectContext, guards the corpus (served only for the default;
  others get NotServedPlaceholder — decouples this slice from Plan B).
- Directory at / (2+ projects) with N=1 redirect into the single project;
  ProjectSwitcher in deployment chrome; entry-noun by project type.
- VITE_APP_NAME hard cut: removed from vite.config + index.html; the 6 brand
  reads now use deployment.name via context; static <title>RFC</title> + JS
  document.title. Internal /rfc·/proposals links → /p/<project>/e|proposals
  via lib/entryPaths.

Backend:
- GET /api/deployment returns default_project_id (the guard contract).
- Server-side 308s: /rfc/<slug>, /rfc/<slug>/pr/<n>, /proposals/<n> →
  /p/<default>/… . nginx (testing + prod) routes /rfc/ and /proposals/ to
  the backend.

Tests: 3 new backend redirect/deployment tests (438 pass); Vitest unit for
DeploymentProvider, ProjectLayout (theme/guard/404), Directory (11 pass);
clean build with no VITE_APP_NAME. Playwright e2e deferred until Tier-1 seeds
a registry (see CHANGELOG 0.35.0 step 5).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/RFCView.jsx

@@ -46,6 +46,7 @@ import GraduateDialog from './GraduateDialog.jsx'
 import InvitationsModal from './InvitationsModal.jsx'
 import { claimOwnership, retireRFC, unretireRFC } from '../api'
 import { EVENTS, track } from '../lib/analytics'
+import { entryPath, entryPrPath, useProjectId } from '../lib/entryPaths'
 
 const MANUAL_IDLE_MS = 5 * 60 * 1000   // §8.6 idle window; exact value is impl detail.
 const MANUAL_DEBOUNCE_MS = 800
@@ -68,6 +69,7 @@ export default function RFCView({ viewer }) {
   const { slug } = useParams()
   const [searchParams, setSearchParams] = useSearchParams()
   const navigate = useNavigate()
+  const pid = useProjectId()
 
   const branchParam = searchParams.get('branch') || 'main'
 
@@ -178,11 +180,11 @@ export default function RFCView({ viewer }) {
     try {
       const res = await unretireRFC(slug)
       getRFC(slug).then(setEntry).catch(() => {})
-      if (res?.state) navigate(`/rfc/${slug}`)
+      if (res?.state) navigate(entryPath(pid, slug))
     } catch (err) {
       setActionError(err.message)
     }
-  }, [slug, navigate])
+  }, [slug, navigate, pid])
 
   // Load main view + branch view whenever slug/branch changes.
   useEffect(() => {
@@ -634,7 +636,7 @@ export default function RFCView({ viewer }) {
           {openPRForBranch && (
             <a
               className="btn-link"
-              href={`/rfc/${slug}/pr/${openPRForBranch.pr_number}`}
+              href={entryPrPath(pid, slug, openPRForBranch.pr_number)}
               title="View the open PR for this branch"
             >
               PR #{openPRForBranch.pr_number} →
@@ -667,7 +669,7 @@ export default function RFCView({ viewer }) {
                   const result = await claimOwnership(slug)
                   if (result?.noop) return
                   if (result?.pr_number) {
-                    navigate(`/rfc/${slug}/pr/${result.pr_number}`)
+                    navigate(entryPrPath(pid, slug, result.pr_number))
                   }
                 } catch (err) {
                   setClaimError(err.message)
@@ -928,7 +930,7 @@ export default function RFCView({ viewer }) {
           onClose={() => setShowPRModal(false)}
           onOpened={(prNumber) => {
             setShowPRModal(false)
-            navigate(`/rfc/${slug}/pr/${prNumber}`)
+            navigate(entryPrPath(pid, slug, prNumber))
           }}
         />
       )}
@@ -980,7 +982,7 @@ export default function RFCView({ viewer }) {
             // Refresh main view so the new open PR surfaces in the
             // breadcrumb meta count immediately.
             getRFCMain(slug).then(setMainView).catch(() => {})
-            navigate(`/rfc/${slug}/pr/${prNumber}`)
+            navigate(entryPrPath(pid, slug, prNumber))
           }}
         />
       )}