Refactor terminology and update UI for archiving feature

- Changed button text and messages from "crawl" to "archive" for clarity.
- Updated HTML elements to reflect the new terminology and improve user guidance.
- Modified footer content to emphasize local-first archiving and provide source link.
- Added a link to the project's repository in the index page and test to ensure it appears.

app/static/app.js

@@ -606,7 +606,7 @@ form.addEventListener("submit", async (event) => {
 
   setMessage("");
   submitButton.disabled = true;
-  submitButton.querySelector("span").textContent = "Creating crawl";
+  submitButton.querySelector("span").textContent = "Preparing archive";
   try {
     const job = await request("/api/captures", {
       method: "POST",
@@ -625,14 +625,14 @@ form.addEventListener("submit", async (event) => {
       }),
     });
     upsertJob(job);
-    setMessage("Crawl queued. This browser will reconnect to it automatically.", "success");
+    setMessage("Archive queued. This browser will reconnect to it automatically.", "success");
     urlInput.value = "";
     void loadPublicStats();
   } catch (error) {
     setMessage(error.message);
   } finally {
     submitButton.disabled = false;
-    submitButton.querySelector("span").textContent = "Start private crawl";
+    submitButton.querySelector("span").textContent = "Start archive";
   }
 });