tauri-app: settings view + profile polish

- App.svelte: new 'settings' view with account/actions/about sections,
  sign-out button, pdsBase()/appviewBase() helpers, showError wired
  into logout, profile gains open-in-browser + sign-out + recent-posts
  heading
- NavRail: add settings item + gear icon, View union extended to 5
- tests: NavRail.test.ts now expects 5 buttons + covers settings click,
  NavRailHarness View type extended

crates/tauri-app/src/lib/components/NavRail.svelte

@@ -4,7 +4,7 @@
   // `$bindable`, use a callback prop to bubble state changes up to
   // the parent.
 
-  type View = "home" | "compose" | "profile" | "search";
+  type View = "home" | "compose" | "profile" | "search" | "settings";
 
   let {
     view = "home",
@@ -19,6 +19,7 @@
     { id: "compose", label: "compose", key: "c", icon: "compose" },
     { id: "profile", label: "profile", key: "p", icon: "profile" },
     { id: "search", label: "search", key: "/", icon: "search" },
+    { id: "settings", label: "settings", key: ",", icon: "settings" },
   ];
 </script>
 
@@ -44,6 +45,11 @@
           <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6">
             <circle cx="12" cy="8" r="4"/><path d="M4 21c0-4 4-7 8-7s8 3 8 7"/>
           </svg>
+        {:else if item.icon === "settings"}
+          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+            <circle cx="12" cy="12" r="3"/>
+            <path d="M19.4 15a1.7 1.7 0 0 0 .3 1.8l.1.1a2 2 0 1 1-2.8 2.8l-.1-.1a1.7 1.7 0 0 0-1.8-.3 1.7 1.7 0 0 0-1 1.5V21a2 2 0 1 1-4 0v-.1a1.7 1.7 0 0 0-1-1.5 1.7 1.7 0 0 0-1.8.3l-.1.1a2 2 0 1 1-2.8-2.8l.1-.1a1.7 1.7 0 0 0 .3-1.8 1.7 1.7 0 0 0-1.5-1H3a2 2 0 1 1 0-4h.1a1.7 1.7 0 0 0 1.5-1 1.7 1.7 0 0 0-.3-1.8l-.1-.1a2 2 0 1 1 2.8-2.8l.1.1a1.7 1.7 0 0 0 1.8.3h.1a1.7 1.7 0 0 0 1-1.5V3a2 2 0 1 1 4 0v.1a1.7 1.7 0 0 0 1 1.5 1.7 1.7 0 0 0 1.8-.3l.1-.1a2 2 0 1 1 2.8 2.8l-.1.1a1.7 1.7 0 0 0-.3 1.8v.1a1.7 1.7 0 0 0 1.5 1H21a2 2 0 1 1 0 4h-.1a1.7 1.7 0 0 0-1.5 1z"/>
+          </svg>
         {:else}
           <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6">
             <circle cx="11" cy="11" r="7"/><path d="m20 20-3-3"/>

crates/tauri-app/src/lib/components/NavRail.test.ts

@@ -29,10 +29,10 @@ async function mountHarness() {
 }
 
 describe("NavRail (callback-prop pattern)", () => {
-  it("renders 4 buttons with home active", async () => {
+  it("renders 5 buttons with home active", async () => {
     await mountHarness();
     const btns = target.querySelectorAll("button.rail__btn");
-    expect(btns.length).toBe(4);
+    expect(btns.length).toBe(5);
     expect(btns[0].classList.contains("active")).toBe(true);
     expect(target.querySelector('[data-testid="view-value"]')?.textContent).toBe("home");
   });
@@ -56,5 +56,10 @@ describe("NavRail (callback-prop pattern)", () => {
     await tick();
     expect(target.querySelector('[data-testid="view-value"]')?.textContent).toBe("profile");
     expect(btns[2].classList.contains("active")).toBe(true);
+
+    btns[4].dispatchEvent(new MouseEvent("click", { bubbles: true }));
+    await tick();
+    expect(target.querySelector('[data-testid="view-value"]')?.textContent).toBe("settings");
+    expect(btns[4].classList.contains("active")).toBe(true);
   });
 });

crates/tauri-app/src/lib/components/NavRailHarness.svelte

@@ -5,7 +5,7 @@
 
   import NavRail from "./NavRail.svelte";
 
-  type View = "home" | "compose" | "profile" | "search";
+  type View = "home" | "compose" | "profile" | "search" | "settings";
   let view: View = $state("home");
 </script>