Embed admin portal as its own app in the jar behind buildWithPortal (#6911)

## What

Lets the admin portal ("Stirling Processor") ship **inside the JAR**,
gated by a build flag. On `main` the portal already exists as a lazy
`/portal/*` route in the editor but isn't included in production builds
and isn't reachable in a login-enabled server. This PR makes it a
**flag-gated, directly-navigable** part of the editor bundle, and wires
it into the PR preview deployment so it can be tried live.

It keeps the exact architecture `main` uses (portal = a lazy chunk of
the editor, not a separate app), so it inherits all the editor's global
providers/styles and there's no second build to maintain.

## How

**Frontend - gate the existing lazy route**
([`adminRouteExtensions.tsx`](frontend/editor/src/proprietary/routes/adminRouteExtensions.tsx))
```ts
const includePortal = import.meta.env.VITE_INCLUDE_PORTAL === "true" || import.meta.env.DEV;
const PortalApp = includePortal ? lazy(() => import("@portal/PortalApp")) : null;
```
Vite bakes the env to a literal, so when off the dynamic import is
**tree-shaken out entirely** (no `PortalApp` chunk emitted). Always on
in dev. `VITE_INCLUDE_PORTAL` is typed in `vite-env.d.ts` and declared
(default `false`) in `editor/.env`.

**Gradle** ([`build.gradle`](app/core/build.gradle)) -
`-PbuildWithPortal=true` forces `buildWithFrontend=true` and sets
`VITE_INCLUDE_PORTAL=true` on the editor build. Process-env takes
priority over `.env`, so the flag wins for JAR builds while plain `vite
build` / Cloudflare Pages default to off.

**Backend - make the shell reachable**
([`RequestUriUtils`](app/common/src/main/java/stirling/software/common/util/RequestUriUtils.java))
- permits `/portal` + `/portal/*` as public SPA routes. The editor keeps
its JWT in localStorage (not a cookie), so a direct nav/refresh to
`/portal` isn't authenticated at the server and would otherwise redirect
to `/login` and never load. Serving the shell pre-auth (like the editor
root already is) lets it load; **access control is unchanged** - the
portal has its own auth gate + `RequirePortalAccess`, and its data APIs
stay protected.

**Docker** - the embedded Dockerfiles take `ARG BUILD_PORTAL=false` →
`-PbuildWithPortal=${BUILD_PORTAL}`. Default off, so official
`push-docker` images do **not** bundle the portal.

**CI - scoped to the PR preview deploy only**
([`PR-Auto-Deploy-V2.yml`](.github/workflows/PR-Auto-Deploy-V2.yml)) -
the one job that builds the JAR and comments owns all portal wiring:
passes `BUILD_PORTAL=true`, enables the portal's backend features
(`POLICIES_ENABLED`, `STIRLING_BILLING_ACCOUNT_LINK_ENABLED`), and adds
an "Admin portal included" line (linking `/portal` via the direct IP) to
the deployment comment. `push-docker`, `build.yml`, `test-build-docker`,
and the shared paths-filter are untouched.

## Validation (real, in the JAR)

Built and booted the JAR with `-PbuildWithPortal=true` and login
enabled:
- `/portal` and `/portal/users` load via direct nav and render **fully
themed** (dark surfaces, gradients, filled buttons).
- Editor-only build (`-PbuildWithFrontend=true`, no portal flag) →
editor ships, **0 portal chunks** (tree-shaken).
- `-PbuildWithPortal=true` → `PortalApp` chunk present.

Green: `frontend:check:all` (typecheck all variants, lint, format,
build, tests incl. the `VITE_*` env guard), backend compile,
`RequestUriUtilsTest`, spotless.

## Notes

- **Official images never bundle the portal** (Dockerfile default off);
only the PR preview does. Flip `BUILD_PORTAL` / `-PbuildWithPortal` to
include it elsewhere.
- The `/portal` shell being public is the one deviation from `main`, and
it's required for the route to be reachable at all in a login-enabled
server; data access is still fully gated.

docker/embedded/Dockerfile.ultra-lite

@@ -40,12 +40,15 @@ RUN ./gradlew dependencies --no-daemon || true
 COPY . .
 
 # Build ultra-lite JAR with embedded frontend (minimal features).
+# Embed the admin portal app at /portal when the deploy workflow flags it.
+ARG BUILD_PORTAL=false
 # Bundle only the JPDFium native for this image's target arch.
 ARG TARGETARCH
 RUN JPDFIUM_PLATFORM="$([ "$TARGETARCH" = arm64 ] && echo linux-arm64 || echo linux-x64)" && \
     DISABLE_ADDITIONAL_FEATURES=true \
     ./gradlew clean build \
       -PbuildWithFrontend=true \
+      -PbuildWithPortal=${BUILD_PORTAL} \
       -PjpdfiumPlatforms="$JPDFIUM_PLATFORM" \
       -x spotlessApply -x spotlessCheck -x test -x sonarqube \
       --no-daemon