feat(frontend): Vue 3 wizard UI (nostr login, episode upload, go-live)

- NIP-07 login → NIP-98 signed request → session cookie
- episode wizard: pick/create podcast (incl. lightning address question),
  browser-side sha256 + BUD-02 blossom upload with progress, feed result page
- live wizard + stream dashboard: OBS server/key (shown once, rotatable),
  browser WHIP publishing (camera or screen), hls.js live preview,
  publish-recording-as-episode flow
- settings view: external blossom URL, relay list, public URL (admin only)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/lib/blossom.ts

@@ -0,0 +1,76 @@
+// Browser-direct Blossom (BUD-02) upload: hash locally, sign the kind-24242
+// authorization with the user's NIP-07 extension, PUT straight to the blossom
+// server. The file never transits podpuddle.
+
+import { nip07 } from './nip07';
+
+export async function sha256File(file: File, onProgress?: (frac: number) => void): Promise<string> {
+  // crypto.subtle needs the whole buffer; fine for podcast-sized mp4s (~2 GB cap).
+  const buf = await file.arrayBuffer();
+  onProgress?.(0.5);
+  const digest = await crypto.subtle.digest('SHA-256', buf);
+  onProgress?.(1);
+  return [...new Uint8Array(digest)].map((b) => b.toString(16).padStart(2, '0')).join('');
+}
+
+export interface BlossomUpload {
+  sha256: string;
+  size: number;
+  url: string;
+}
+
+export async function uploadToBlossom(
+  blossomUrl: string,
+  file: File,
+  sha256: string,
+  onProgress?: (frac: number) => void,
+): Promise<BlossomUpload> {
+  const now = Math.floor(Date.now() / 1000);
+  const auth = await nip07().signEvent({
+    kind: 24242,
+    created_at: now,
+    content: `Upload ${file.name}`,
+    tags: [
+      ['t', 'upload'],
+      ['x', sha256],
+      ['expiration', String(now + 600)],
+    ],
+  });
+
+  const base = blossomUrl.replace(/\/+$/, '');
+  // XHR instead of fetch for upload progress events.
+  await new Promise<void>((resolve, reject) => {
+    const xhr = new XMLHttpRequest();
+    xhr.open('PUT', `${base}/upload`);
+    xhr.setRequestHeader('authorization', `Nostr ${btoa(JSON.stringify(auth))}`);
+    xhr.setRequestHeader('content-type', file.type || 'video/mp4');
+    xhr.upload.onprogress = (e) => {
+      if (e.lengthComputable) onProgress?.(e.loaded / e.total);
+    };
+    xhr.onload = () => {
+      if (xhr.status >= 200 && xhr.status < 300) resolve();
+      else reject(new Error(`blossom upload failed: ${xhr.status} ${xhr.responseText.slice(0, 200)}`));
+    };
+    xhr.onerror = () => reject(new Error('blossom upload failed: network error'));
+    xhr.send(file);
+  });
+
+  return { sha256, size: file.size, url: `${base}/${sha256}` };
+}
+
+/** Read the media duration (seconds) from a local file, for itunes:duration. */
+export function probeDuration(file: File): Promise<number | null> {
+  return new Promise((resolve) => {
+    const el = document.createElement('video');
+    el.preload = 'metadata';
+    el.onloadedmetadata = () => {
+      URL.revokeObjectURL(el.src);
+      resolve(Number.isFinite(el.duration) ? Math.round(el.duration) : null);
+    };
+    el.onerror = () => {
+      URL.revokeObjectURL(el.src);
+      resolve(null);
+    };
+    el.src = URL.createObjectURL(file);
+  });
+}