Update Cloudflare R2 upload to use minimal permissions and add progress bar

- Removed requirement for Cloudflare API Token, Zone ID, and Worker Token from Upload Modal and R2Service.
- Simplified R2 configuration to require only Account ID, S3 Access Keys, and a user-provided Public Bucket URL.
- Added a read-only field in Upload Modal displaying the derived target bucket name (npub-based) for user reference.
- Implemented client-side torrent info hash calculation using `WebTorrent` (via `js/utils/torrentHash.js`) to generate magnet links before upload.
- Added a visual upload progress bar to the Upload Modal.
- Updated `js/r2.js` to ensure the Public Bucket URL always includes the `https://` protocol.

js/utils/torrentHash.js

@@ -0,0 +1,62 @@
+import WebTorrent from "../webtorrent.min.js";
+import { userLogger } from "./logger.js";
+
+/**
+ * Calculates the torrent infoHash for a given file client-side.
+ * This operation requires reading and hashing the entire file, so it may take time for large files.
+ *
+ * @param {File} file - The file object to hash.
+ * @returns {Promise<string>} - Resolves with the hex encoded infoHash.
+ */
+export async function calculateTorrentInfoHash(file) {
+  if (!file) {
+    throw new Error("No file provided for hashing.");
+  }
+
+  // Create a temporary client just for hashing.
+  // We disable trackers and dht/lsd to keep it quiet and fast (local only).
+  const client = new WebTorrent({
+    tracker: false,
+    dht: false,
+    lsd: false,
+    webSeeds: false,
+  });
+
+  return new Promise((resolve, reject) => {
+    // Seed the file. This calculates the infoHash.
+    // We use destroyStoreOnDestroy: true to clean up memory/storage afterwards.
+    try {
+        client.seed(
+          file,
+          {
+            announce: [], // No trackers
+            destroyStoreOnDestroy: true,
+            name: file.name,
+          },
+          (torrent) => {
+            const infoHash = torrent.infoHash;
+            // Destroy the client and the torrent data immediately.
+            client.destroy((err) => {
+              if (err) {
+                userLogger.warn("Error destroying temporary hashing client:", err);
+              }
+              if (infoHash) {
+                resolve(infoHash);
+              } else {
+                reject(new Error("Failed to calculate info hash."));
+              }
+            });
+          }
+        );
+
+        client.on("error", (err) => {
+            userLogger.error("WebTorrent client error during hashing:", err);
+            client.destroy();
+            reject(err);
+        });
+    } catch (err) {
+        client.destroy();
+        reject(err);
+    }
+  });
+}