v0.320.0: FileBrowser is part of the box again; every app says where its login is; a „Fájlok" button

FileBrowser (and traefik, cloudflared, samba) has no app.yaml, so Deployed is false. Since v0.315.0 the
app page read Deployed alone and showed FileBrowser "not installed", with Install and without its login.
A protected infra stack is now installed by definition on the app page (Deployed || Protected, as every
other surface already counted): settings/guide/log tabs, Restart only, no install page, no data tab.
The Install press would have deployed the infra stack as an app: DeployStack and the deploy API now
refuse a protected stack.

In the operator state (the box does not know FileBrowser's password - both demo boxes) the login panel
offers "Új jelszó beállítása": the file browser's own CLI with the server stopped (spiked on demo-hp:
new 200, old 401, users/shares/settings unchanged), verified, stored encrypted, state generated.

Every installed app's settings tab has the login panel with exactly one answer: the box's fields, the
login the app wrote (InitialCreds), or a sentence chosen by the catalog's new app_info.login_kind
(first_visit default, email, none; none behind the family gate says the family sign-in is the login).

"Fájlok ↗" opens the library folder, else the first declared folder, else a media app's first present
drive's media folder. The data tab lists each drive's media folders; a folder whose drive is not bound
into FileBrowser is text, never a link.

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/api/router.go

@@ -437,6 +437,8 @@ func deployStatusFor(err error) int {
 	switch {
 	case errors.Is(err, stacks.ErrAlreadyDeployed), errors.Is(err, stacks.ErrKeptDataChoice):
 		return http.StatusConflict
+	case errors.Is(err, stacks.ErrProtectedStack):
+		return http.StatusForbidden
 	case errors.Is(err, stacks.ErrRequiredField), errors.Is(err, stacks.ErrPathMissing), errors.Is(err, stacks.ErrNeedsDrive),
 		errors.Is(err, stacks.ErrNotEnoughMemory):
 		return http.StatusBadRequest
@@ -473,6 +475,14 @@ func (r *Router) deployStack(w http.ResponseWriter, req *http.Request, name stri
 		return
 	}
 
+	// v0.320.0: a protected infra stack is part of the box, never an app to install. Refused here, before the
+	// kept-data check or anything else that reads the request, and again inside DeployStack for every other caller.
+	if st, ok := r.stackMgr.GetStack(name); ok && (st.Protected || r.cfg.IsProtectedStack(name)) {
+		r.logger.Printf("[WARN] [api] Deploy refused for %s: a protected infra stack is part of the box", name)
+		writeJSON(w, http.StatusForbidden, apiResponse{OK: false, Error: r.msg(req, "api.deploy.part_of_box")})
+		return
+	}
+
 	// Prevention layer (storage-split): refuse a deploy when the Docker-data volume is at/under its
 	// reserved buffer, so customer apps can't fill the volume the infra containers (controller,
 	// traefik, cloudflared, filebrowser) depend on. Fail-OPEN on a measurement error — the buffer is