feat(install): add Windows PowerShell installer and copy buttons on site

Add install.ps1 mirroring install.sh for Windows: arch detection,
release zip download, binary extraction, user PATH update.

- copy install.ps1 to site public/ at build time (copy-install.mjs)
- serve /install.ps1 with text/plain Content-Type (vercel.json)
- add PowerShell one-liner to install page and README
- bump install.ps1 default version in bump_version.sh
- add CopyButton component next to every install command line

site/src/components/CopyButton.astro

@@ -0,0 +1,54 @@
+---
+interface Props {
+  text: string;
+  class?: string;
+}
+const { text, class: className } = Astro.props;
+---
+<button
+  type="button"
+  class:list={[
+    "copy-btn rounded p-1.5 text-overlay transition-colors hover:bg-mantle hover:text-text",
+    className,
+  ]}
+  data-copy={text}
+  aria-label="Copy command to clipboard"
+  title="Copy"
+>
+  <svg class="copy-icon h-4 w-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+    <rect x="9" y="9" width="13" height="13" rx="2" ry="2"></rect>
+    <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"></path>
+  </svg>
+  <svg class="check-icon hidden h-4 w-4 text-green" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+    <path d="M20 6 9 17l-5-5"></path>
+  </svg>
+</button>
+<script>
+  const RESET_DELAY_MS = 1500;
+
+  const handleCopy = async (button: HTMLElement) => {
+    const text = button.getAttribute("data-copy") ?? "";
+    try {
+      await navigator.clipboard.writeText(text);
+    } catch {
+      return;
+    }
+
+    const copyIcon = button.querySelector(".copy-icon");
+    const checkIcon = button.querySelector(".check-icon");
+    copyIcon?.classList.add("hidden");
+    checkIcon?.classList.remove("hidden");
+
+    window.setTimeout(() => {
+      copyIcon?.classList.remove("hidden");
+      checkIcon?.classList.add("hidden");
+    }, RESET_DELAY_MS);
+  };
+
+  document.addEventListener("click", (event) => {
+    const button = (event.target as HTMLElement)?.closest<HTMLElement>(".copy-btn");
+    if (button) {
+      handleCopy(button);
+    }
+  });
+</script>

site/src/components/InstallTabs.astro

@@ -1,4 +1,6 @@
 ---
+import CopyButton from "./CopyButton.astro";
+
 interface Method { id: string; label: string; cmd: string; }
 interface Props { methods: Method[]; }
 const { methods } = Astro.props;
@@ -14,11 +16,10 @@ const { methods } = Astro.props;
     ))}
   </div>
   {methods.map((m, i) => (
-    <pre
-      class="install-panel m-0 overflow-auto bg-base px-4 py-4 text-sm text-text"
-      data-id={m.id}
-      hidden={i !== 0}
-    ><code>{m.cmd}</code></pre>
+    <div class="install-panel relative" data-id={m.id} hidden={i !== 0}>
+      <pre class="m-0 overflow-auto bg-base px-4 py-4 pr-12 text-sm text-text"><code>{m.cmd}</code></pre>
+      <CopyButton text={m.cmd} class="absolute right-2 top-2" />
+    </div>
   ))}
 </div>
 <script is:inline>

site/src/pages/install.astro

@@ -3,9 +3,11 @@ import Base from "../layouts/Base.astro";
 import Nav from "../components/Nav.astro";
 import Footer from "../components/Footer.astro";
 import InstallTabs from "../components/InstallTabs.astro";
+import CopyButton from "../components/CopyButton.astro";
 import { DOCS_URL } from "../consts";
 
 const script = "curl --proto '=https' --tlsv1.2 -sSLf https://termscp.rs/install.sh | sh";
+const psScript = "irm https://termscp.rs/install.ps1 | iex";
 
 const methods = [
   { id: "cargo", label: "Cargo", cmd: "cargo install termscp --locked" },
@@ -28,10 +30,24 @@ const methods = [
       <div class="flex items-center gap-2 border-b border-line px-3 py-2 text-xs text-overlay">
         <span class="text-green">$</span> Linux · macOS · BSD
       </div>
-      <pre class="m-0 overflow-auto bg-base px-4 py-4 text-sm text-text"><code>{script}</code></pre>
+      <div class="relative">
+        <pre class="m-0 overflow-auto bg-base px-4 py-4 pr-12 text-sm text-text"><code>{script}</code></pre>
+        <CopyButton text={script} class="absolute right-2 top-2" />
+      </div>
     </div>
     <p class="mt-2 text-xs text-overlay">Requires <span class="text-text">curl</span>. macOS uses Homebrew if available, otherwise builds from source.</p>
 
+    <div class="mt-6 rounded-lg border border-line bg-mantle p-1">
+      <div class="flex items-center gap-2 border-b border-line px-3 py-2 text-xs text-overlay">
+        <span class="text-green">&gt;</span> Windows (PowerShell)
+      </div>
+      <div class="relative">
+        <pre class="m-0 overflow-auto bg-base px-4 py-4 pr-12 text-sm text-text"><code>{psScript}</code></pre>
+        <CopyButton text={psScript} class="absolute right-2 top-2" />
+      </div>
+    </div>
+    <p class="mt-2 text-xs text-overlay">Downloads the latest release and adds <span class="text-text">termscp</span> to your user PATH.</p>
+
     <h2 class="mt-10 mb-3 text-lg text-text">Package managers</h2>
     <InstallTabs methods={methods} />