[ui] B2 storage: use pipx for the CORS CLI install + rename secret field to "Application Key"

- CORS setup helper: the Backblaze B2 instructions now say `pipx install b2` instead of
  `pip install b2` (the recommended way to install a CLI tool).
- Storage form: for the Backblaze B2 provider the "Secret Access Key" field is now
  labelled "Application Key" to match B2's own terminology (the secret half of an
  Application Key). Other providers keep "Secret Access Key".

Test updated to assert the pipx instruction. Build + lint clean.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/ui/profileModal/ProfileStorageController.js

@@ -437,6 +437,13 @@ export class ProfileStorageController {
       this.storageRegionInput.placeholder = "auto";
     }
 
+    // B2 calls the secret an "Application Key" — match its terminology.
+    const secretLabel =
+      this.storageSecretKeyInput?.parentElement?.querySelector("span");
+    if (secretLabel) {
+      secretLabel.textContent = isB2 ? "Application Key" : "Secret Access Key";
+    }
+
     if (this.storageR2Helper) {
       this.storageR2Helper.classList.toggle("hidden", !isR2);
     }

js/ui/profileModal/storageCorsHelp.js

@@ -84,7 +84,7 @@ export function buildCorsHelpContent({ provider, origins, bucket, endpoint } = {
       cmdLabel: "Apply it (B2 command-line tool)",
       cmd: buildB2CorsCommand(bucket, rules),
       notes:
-        "1. Install the B2 CLI (pip install b2).\n" +
+        "1. Install the B2 CLI (pipx install b2).\n" +
         "2. Run the command above (it authorizes, then sets the rules).\n" +
         "3. Wait ~1 minute, then retry your upload.\n" +
         "Tip: a B2 application key with the writeBucketCors capability lets bitvid set " +

tests/storage-cors-help.test.mjs

@@ -70,7 +70,7 @@ test("content for Backblaze B2 uses B2-native rules + the b2 CLI", () => {
   assert.match(c.cmd, /^b2 update-bucket /);
   assert.match(c.cmdLabel, /B2 command-line/i);
   assert.ok(JSON.parse(c.json)[0].allowedOperations.includes("s3_put"));
-  assert.match(c.notes, /b2 CLI|pip install b2/i);
+  assert.match(c.notes, /pipx install b2/i);
 });
 
 test("content for Custom S3 uses standard S3 CORS + the AWS CLI", () => {