feat(manager-core,orchestrator-core): multi-app scoping (Phase 3b)

Apps become the isolation boundary for scripts, routes, domains, and
later data. Doing this now — while the surface is small — avoids
several migrations on populated tables once v1.1 data-plane services
ship.

Schema (migration 0005_apps.sql):
- New tables: apps, app_domains (with shape_key UNIQUE for collision
  detection), app_slug_history (for permanent slug-rename redirects).
- app_id added to scripts, routes, execution_logs (non-null, cascading
  rules per row).
- Script-name uniqueness becomes per-app; the route unique index is
  swapped for an app-scoped version.
- The "default" app is seeded unconditionally with a localhost claim;
  existing scripts/routes backfill into it. Fresh installs additionally
  get the Hello World seed via seed_hello_world_if_fresh after
  migrations run (idempotent — only fires when the default app has no
  scripts).

Orchestrator dispatch is two-phase: AppDomainTable resolves Host →
app_id (most-specific match wins, exact beats wildcard), then the
existing route matcher runs against that app's partitioned slice via
RouteTable. Unknown hosts return 404 at the app layer with a clear
message; /api/v1/execute/{id} still works as the implicit
__internal__ claim, decoupled from any public domain.

Manager API: full CRUD for /api/v1/admin/apps/* and
/api/v1/admin/apps/{id_or_slug}/domains/*, with slug:check + force
takeover semantics implementing the rename-history flow (two-step
check → confirm, never a single endpoint). Script create requires
app_id; list accepts ?app= filter. Route create validates host
against the parent app's claims; conflict detection stays strictly
intra-app.

Dashboard: /admin/apps and /admin/apps/{slug} (overview + scripts +
domains + settings tabs, with slug-history-aware redirects). Root
path redirects to the apps list. Script detail page gains an app
breadcrumb and threads app_id into the route preview.

Deferred per design: per-app admin roles. The require_admin middleware
remains the seam where role checks will slot in later.

Blueprint §11.5 and roadmap updated to reflect what shipped; docs/
versioning.md notes the schema 3 → 5 bump.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/manager-core/seeds/hello.rhai

@@ -0,0 +1,15 @@
+// Hello World — the reference example seeded into the default app on
+// fresh installs. Bound to GET /hello.
+
+let who = ctx.request.body;
+let name = if who != () && type_of(who) == "map" && who.contains("name") {
+    who.name
+} else {
+    "world"
+};
+
+return #{
+    statusCode: 200,
+    headers: #{ "Content-Type": "application/json" },
+    body: #{ message: `Hello, ${name}!` }
+};