Generalize podcast-specific UI for study-only users

Other people using this app just want to do personal Bible study, not
produce a podcast episode, so the always-visible chrome (chunk
metadata, DOCX import, exports) now says "Session" instead of
"Episode" and marks podcast-only fields as optional. The "Prepare for
Podcast" prompt no longer hardcodes "Verse by Verse with Nate" for
every user — it now pulls from a new "Podcast / show name" field in
Account Settings, so it still works exactly as before once you set
yours, but produces a sensible generic prompt for anyone who hasn't.
Also added an explanatory blurb to the session-list import page and
loosened its docx parser to accept "Session N — Title" in addition to
"Ep. N — Title".

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

server/db.js

@@ -58,6 +58,11 @@ export function initDb() {
     `);
   }
 
+  // Older databases predate the podcast-name profile setting.
+  if (!userCols.some((c) => c.name === 'podcast_name')) {
+    db.exec('ALTER TABLE users ADD COLUMN podcast_name TEXT');
+  }
+
   console.log(`SQLite database ready at ${DB_PATH}`);
 }
 
@@ -98,7 +103,8 @@ function parseUserRow(row) {
 
 const USER_SELECT = `
   SELECT id, email, password_hash AS passwordHash, created_at AS createdAt,
-         totp_secret AS totpSecret, totp_enabled AS totpEnabled, backup_codes AS backupCodesRaw
+         totp_secret AS totpSecret, totp_enabled AS totpEnabled, backup_codes AS backupCodesRaw,
+         podcast_name AS podcastName
   FROM users
 `;
 
@@ -124,6 +130,11 @@ export function disableTotp(userId) {
   `).run(userId);
 }
 
+/** Sets or clears the show name used in the "Prepare for Podcast" prompt. */
+export function setPodcastName(userId, podcastName) {
+  db.prepare('UPDATE users SET podcast_name = ? WHERE id = ?').run(podcastName || null, userId);
+}
+
 /** Rewrites the remaining backup-code hashes after one is used (single-use codes). */
 export function setBackupCodeHashes(userId, backupCodeHashes) {
   db.prepare('UPDATE users SET backup_codes = ? WHERE id = ?').run(JSON.stringify(backupCodeHashes), userId);