feat(frontend): panneau Settings Deployment et gateway serveur desktop (#68 F1+F2)

Donne à l'utilisateur la surface pour activer le serveur depuis l'app.

- `features/settings/` : `SettingsView`, `DeploymentSettings`, `useDeployment`.
- `adapters/desktopServer.ts` + port `DesktopServerGateway` et DTO associés ;
  adapters mock et http/unsupported alignés (le mode web n'expose pas le
  contrôle du serveur qui l'héberge).
- `ProjectsView` : le `showSettings: boolean` devient une navigation interne
  `AI Profiles` / `Deployment`. Le libellé alternant « Close AI Profiles »
  disparaît — Settings existait déjà dans cette vue, la surface évolue au lieu
  d'ajouter un `PanelId`.

CORRECTION D'UN BRIEF FAUX, remontée spontanément par DevFrontend et qui mérite
de survivre : le cadrage décrivait le mode `remoteProxyOtherMachine` avec deux
champs. `validate_settings` en exige un troisième, `lanBindAddress`, et rejette
loopback comme unspecified. Construit selon la spec, chaque save et chaque start
en mode 3 aurait échoué — le lot serait parti vert et cassé. Le panneau expose
donc un select alimenté par `candidateLanAddresses` fourni par le backend :
la règle « le frontend n'invente jamais une IP » tient.

QA ré-exécutée par Git avant merge : `npm run typecheck` exit 0 ·
`npx vitest run` 87 files / 789 passed, 0 échec.

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

frontend/src/features/settings/SettingsView.tsx

@@ -0,0 +1,85 @@
+/**
+ * `SettingsView` — the Settings surface shell (ticket #68).
+ *
+ * Settings is a **main surface**, not a dockable project view: it deliberately
+ * has no `PanelId` and stays outside the `viewPlacement` model. It takes over
+ * the main area while the menu bar stays visible above it.
+ *
+ * Ticket #68 gives it a second section, so the section list becomes real
+ * navigation (a left column) instead of the old single toggle. That also kills
+ * the alternating "Close AI Profiles" menu label, which never scaled past one
+ * entry: the menu now names sections, the active one is marked, and closing is
+ * an explicit action inside the view.
+ *
+ * `EmbedderSettings` / `ModelServersPanel` are **not** pulled in here — that is
+ * a separate lateral rework. The section list is the seam they would slot into.
+ */
+
+import { Button, cn } from "@/shared";
+import { ProfilesSettings } from "@/features/first-run";
+import { DeploymentSettings } from "./DeploymentSettings";
+
+/** The Settings sections, in menu/nav order. */
+export type SettingsSection = "aiProfiles" | "deployment";
+
+/** Human labels, shared by the nav column and the `Settings` menu. */
+export const SETTINGS_SECTION_LABEL: Record<SettingsSection, string> = {
+  aiProfiles: "AI Profiles",
+  deployment: "Deployment",
+};
+
+/** Section order — the single source of truth for both nav and menu. */
+export const SETTINGS_SECTIONS: SettingsSection[] = ["aiProfiles", "deployment"];
+
+interface SettingsViewProps {
+  section: SettingsSection;
+  onSectionChange: (section: SettingsSection) => void;
+  onClose: () => void;
+}
+
+export function SettingsView({
+  section,
+  onSectionChange,
+  onClose,
+}: SettingsViewProps) {
+  return (
+    <div className="flex min-h-0 flex-1 overflow-hidden">
+      <nav
+        aria-label="settings sections"
+        className="flex w-52 shrink-0 flex-col gap-1 border-r border-border p-3"
+      >
+        {SETTINGS_SECTIONS.map((id) => {
+          const active = id === section;
+          return (
+            <button
+              key={id}
+              type="button"
+              aria-current={active ? "page" : undefined}
+              onClick={() => onSectionChange(id)}
+              className={cn(
+                "rounded-md px-3 py-2 text-left text-sm transition-colors",
+                active
+                  ? "bg-raised font-semibold text-content"
+                  : "text-muted hover:bg-raised hover:text-content",
+              )}
+            >
+              {SETTINGS_SECTION_LABEL[id]}
+            </button>
+          );
+        })}
+
+        <div className="mt-auto pt-2">
+          <Button size="sm" variant="ghost" className="w-full" onClick={onClose}>
+            Close Settings
+          </Button>
+        </div>
+      </nav>
+
+      <div className="flex flex-1 justify-center overflow-y-auto p-6">
+        <div className="w-full max-w-2xl">
+          {section === "aiProfiles" ? <ProfilesSettings /> : <DeploymentSettings />}
+        </div>
+      </div>
+    </div>
+  );
+}