add Server section to the admin panel and setup wizard

Fills in the Server piece of the `/admin/setup` wizard and its
admin-panel counterpart -- Base URL and Edition -- plus the shared
apply/restart plumbing the other wizard steps can plug into.

Highlights:

- `BaseUrlSection` with a Test-URL-then-Confirm flow. "Leave automatic"
  actually clears a manually-set APP_HOME_URL via PATCH /install/prefs
  rather than being a no-op skip, so the label matches the effect.
- `EditionSection` reusing the existing `ToggleEnterpriseWidget` in
  admin-panel mode; a simple Community vs Full Grist picker in wizard
  mode. Availability is a constructor option so storybook can drive
  variants without runtime tricks.
- `PendingChangesManager` + `PartialApplyError`: sections implement a
  small `ConfigSection` interface, the manager batches apply()s,
  restarts the server once at the end when needed, and surfaces partial
  failures with labelled per-section errors.
- Writes go through `PATCH /api/install/prefs` (the consolidated
  envVars write path from c73044a), not a dedicated POST.
- `GET /api/config/server` reads activation prefs + process.env directly,
  bypassing the memoized `getHomeUrl()` so the admin panel reflects
  persisted writes without waiting for the restart.
- The Enterprise admin-panel stub now surfaces the installation ID via
  a shared `buildInstallationIdDisplay` helper extracted from
  `ToggleEnterpriseWidget`. Community builds omit the row since the
  activation-status endpoint isn't mounted there.
- `AdminPanelCss` gains a couple of shared helpers (`buildConfirmedRow`,
  moved `cssDangerText`/`cssErrorText`/`cssHappyText`) that other
  sections can reuse.
- Storybook stories for `BaseUrlSection` and `EditionSection` so UI
  states can be previewed without standing up a server. Aligns with
  the convention in other in-flight wizard branches.
- Browser tests in `test/nbrowser/AdminPanelServer.ts` covering the
  admin-panel item, the Test-and-Confirm flow, persistence through the
  install/prefs endpoint, and the wizard getting-through-without-changes
  and Apply-and-Continue paths.

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

Author: paulfitz

app/client/ui/AdminLeftPanel.ts

@@ -5,6 +5,7 @@ import { AppHeader } from "app/client/ui/AppHeader";
 import * as css from "app/client/ui/LeftPanelCommon";
 import { PageSidePanel } from "app/client/ui/PagePanels";
 import { infoTooltip } from "app/client/ui/tooltips";
+import { theme } from "app/client/ui2018/cssVars";
 import { IconName } from "app/client/ui2018/IconList";
 import { cssLink } from "app/client/ui2018/links";
 import { AdminPanelPage } from "app/common/gristUrls";
@@ -14,6 +15,7 @@ import { getAdminConfig } from "app/common/urlUtils";
 import { Computed, dom, DomContents, MultiHolder, Observable, styled } from "grainjs";
 
 import type { AppModel } from "app/client/models/AppModel";
+import type { RestartBannerController } from "app/client/ui/AdminPanel";
 
 const t = makeT("AdminPanel");
 const testId = makeTestId("test-admin-controls-");
@@ -42,7 +44,11 @@ export function getPageNames() {
   };
 }
 
-export function buildAdminLeftPanel(owner: MultiHolder, appModel: AppModel): PageSidePanel {
+export function buildAdminLeftPanel(
+  owner: MultiHolder,
+  appModel: AppModel,
+  restartBanner?: RestartBannerController,
+): PageSidePanel {
   const pageObs = Computed.create(owner, use => use(urlState().state).adminPanel);
 
   const isSetup = pageObs.get() === "setup";
@@ -77,6 +83,16 @@ export function buildAdminLeftPanel(owner: MultiHolder, appModel: AppModel): Pag
       buildPageEntry("admin", "Home"),
       // TODO: Uncomment when setup page is ready.
       // buildPageEntry("setup", "Settings"),
+      restartBanner ? dom.maybe(restartBanner.isVisible, () =>
+        cssApplyChangesEntry(
+          css.cssPageLink(
+            css.cssPageIcon("Warning"),
+            css.cssLinkText(t("Apply changes")),
+            dom.on("click", () => restartBanner.focus()),
+          ),
+          testId("page-apply-changes"),
+        ),
+      ) : null,
       css.cssSectionHeader(css.cssSectionHeaderText(pageNames.adminControls),
         (adminControlsAvailable ?
           infoTooltip("adminControls", { popupOptions: { placement: "bottom-start" } }) :
@@ -118,3 +134,12 @@ const cssLearnMoreLink = styled(cssLink, `
   gap: 8px;
   align-items: center;
 `);
+
+const cssApplyChangesEntry = styled(css.cssPageEntry, `
+  color: ${theme.dangerText};
+  --icon-color: ${theme.dangerText};
+  cursor: pointer;
+  & .${css.cssPageLink.className} {
+    color: inherit;
+  }
+`);