Rebuild API Server on the PilotVault structure

Mirror PilotVault's API Server layout and add the superadmin console,
plugin system, runtime PocketBase settings, and user/organization
management. The car domain (cars, service records, parts, sharing) is
carried over unchanged apart from the auth switch.

Layout: main.go -> cmd/server/main.go; module carcontrol/api ->
drivervault/apiserver. internal/api is split by concern (auth, users,
orgs, settings, plugins, status, health, respond).

Auth: replace the server-minted HS256 JWT and the sessions collection
with a PocketBase token proxy. /api/auth/login relays PocketBase's
{token, record}, and every protected request re-resolves that token
against PocketBase, so a role change or deletion takes effect at once
instead of waiting out a token. AUTH_SECRET is obsolete and internal/auth
is gone. Per-device session listing/revocation goes with it: PocketBase
tokens are stateless. Changing a password rotates the user's token key,
which invalidates every token already issued.

Roles: add superadmin alongside user/admin, plus an organizations
collection and users.organization. Admins are scoped to their own
organization; superadmins span all of them. Guards prevent changing your
own role, deleting your own account, an admin touching a superadmin, and
deleting an organization that still has members.

Plugins: new internal/plugins package with one contract over two kinds --
builtin (compiled in) and external (any HTTP service, registered at
runtime with no rebuild). State persists to plugins.json; secrets are
masked on read and preserved when saved back at the mask.

PocketBase settings: /api/admin/pb-config applies a new connection at
runtime and persists it to .env. It deliberately does not require a
working service account, so a wrong or unreachable connection can still
be fixed from the panel.

Panel: rebuilt as the superadmin console -- login gate, status, users,
organizations, PocketBase, plugins, and the endpoint reference.

Clients: update the Web App and Phone App for the PocketBase token shape,
the move of user management to /api/users ({users}/{user} envelopes, with
password resets folded into PATCH), and the removal of sessions. Both now
mirror the server's real guards rather than the old last-admin rule, and
parse PocketBase's field-level error shape.

Config: modern POCKETBASE_*/API_ADDR names with legacy PB_*/PORT
fallbacks, so existing .env files keep working. Also fixes /api/status
probing the Web App on 8090 instead of DriverVault's 5173.

Run scripts/setup-pocketbase.mjs to add the organizations collection and
grow users.role; every client must log in once more.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

API Server/internal/api/status.go

@@ -0,0 +1,61 @@
+package api
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+)
+
+// svcHealth is the health of one upstream service, as shown on the panel.
+type svcHealth struct {
+	Status     string `json:"status"` // "ok" | "down"
+	LatencyMs  int64  `json:"latencyMs,omitempty"`
+	HTTPStatus int    `json:"httpStatus,omitempty"`
+	URL        string `json:"url,omitempty"`
+	Error      string `json:"error,omitempty"`
+}
+
+// healthClient is a short-timeout client for probing upstreams so a hung
+// dependency can't stall the status endpoint.
+var healthClient = &http.Client{Timeout: 4 * time.Second}
+
+// probe does a GET against url and classifies the result.
+func probe(ctx context.Context, url string) svcHealth {
+	start := time.Now()
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return svcHealth{Status: "down", URL: url, Error: err.Error()}
+	}
+	resp, err := healthClient.Do(req)
+	lat := time.Since(start).Milliseconds()
+	if err != nil {
+		return svcHealth{Status: "down", URL: url, LatencyMs: lat, Error: err.Error()}
+	}
+	defer resp.Body.Close()
+	_, _ = io.Copy(io.Discard, resp.Body)
+	status := "ok"
+	if resp.StatusCode >= 400 {
+		status = "down"
+	}
+	return svcHealth{Status: status, LatencyMs: lat, HTTPStatus: resp.StatusCode, URL: url}
+}
+
+// GET /api/status — aggregate health of the API Server and its neighbours
+// (PocketBase and the Web App), probed server-side. The panel polls this so the
+// browser never has to reach PocketBase or the Web App directly.
+func (s *Server) handleStatus(w http.ResponseWriter, r *http.Request) {
+	var pbHealth, web svcHealth
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() { defer wg.Done(); pbHealth = probe(r.Context(), s.pb.BaseURL()+"/api/health") }()
+	go func() { defer wg.Done(); web = probe(r.Context(), s.webAppURL()+"/healthz") }()
+	wg.Wait()
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"apiServer":  map[string]any{"status": "ok"},
+		"pocketBase": pbHealth,
+		"webApp":     web,
+	})
+}