feat(web): settings helptext behind a "?" popup instead of inline paragraphs

The Qobuz/Monitor/Discovery help I just added was always-visible and verbose.
Replace each with a compact "?" button (new reusable HelpButton) that opens the
same content in a popup (reuses the Modal), keeping the settings tabs clean.

web tsc + build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/_ui/help-button.tsx

@@ -0,0 +1,25 @@
+"use client";
+
+import { useState, type ReactNode } from "react";
+import { Modal } from "./modal";
+
+/** A small "?" affordance that opens its help content in a popup, keeping settings pages
+ *  uncluttered. */
+export function HelpButton({ title, children }: { title: string; children: ReactNode }) {
+  const [open, setOpen] = useState(false);
+  return (
+    <>
+      <button
+        type="button"
+        className="help-btn"
+        aria-label={`Help: ${title}`}
+        onClick={() => setOpen(true)}
+      >
+        ?
+      </button>
+      <Modal open={open} onClose={() => setOpen(false)} title={title}>
+        <div className="help-body">{children}</div>
+      </Modal>
+    </>
+  );
+}

web/src/app/design.css

@@ -259,7 +259,7 @@ nav.contents .sep { flex: 1; }
 .field.wide { grid-column: 1 / -1; }
 .subhead {
   font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.16em; text-transform: uppercase;
-  color: var(--graphite); margin: 26px 0 2px;
+  color: var(--graphite); margin: 26px 0 2px; display: flex; align-items: center; gap: 10px;
 }
 .field .set { color: var(--accent); }
 .info-panel {
@@ -276,6 +276,16 @@ nav.contents .sep { flex: 1; }
 .help { font-size: 0.8rem; color: var(--graphite); line-height: 1.5; margin: 4px 0 14px; max-width: 62ch; }
 .help b { color: var(--ink); font-weight: 600; }
 .help code { font-family: var(--mono); font-size: 0.85em; }
+/* compact "?" trigger that opens help in a popup */
+.help-btn {
+  font-family: var(--mono); font-size: 0.72rem; line-height: 1; width: 20px; height: 20px;
+  border: 1.5px solid var(--rule-2); border-radius: 50%; background: transparent; color: var(--graphite);
+  cursor: pointer; display: inline-flex; align-items: center; justify-content: center; padding: 0;
+}
+.help-btn:hover { border-color: var(--accent); color: var(--accent); }
+.help-body { font-size: 0.9rem; color: var(--ink); line-height: 1.6; }
+.help-body b { font-weight: 600; }
+.help-body code { font-family: var(--mono); font-size: 0.85em; }
 .info-panel + .info-panel { margin-top: 14px; }
 
 /* ── Modal ────────────────────────────────────────────── */

web/src/app/settings/settings-form.tsx

@@ -2,6 +2,7 @@
 
 import { useEffect, useState } from "react";
 import { PageHead } from "../_ui/page-head";
+import { HelpButton } from "../_ui/help-button";
 
 type Loaded = {
   qobuzEmail: string;
@@ -192,12 +193,14 @@ export function SettingsForm() {
 
       {tab === "Qobuz" ? (
         <form className="settings-section" onSubmit={saveCredentials}>
-          <p className="help">
+          <div className="subhead">
+            Auth token
+            <HelpButton title="Qobuz authentication">
               Lyra signs in to Qobuz with a <b>user ID + auth token</b> — the download engine
               treats these as more reliable than email/password, which Qobuz often rejects. Find
               them in your logged-in Qobuz web session (bundle/app secret + user auth token).
-          </p>
-          <div className="subhead">Auth token</div>
+            </HelpButton>
+          </div>
           <div className="field-grid">
             <label className="field">
               <span>Qobuz user ID</span>
@@ -339,20 +342,22 @@ export function SettingsForm() {
               />
               Automatic monitoring (grab &amp; upgrade)
             </label>
-          </div>
-          <p className="help">
+            <HelpButton title="Monitoring">
               When on, the worker periodically checks your followed artists: it <b>grabs new
               releases</b> as they appear and <b>upgrades</b> owned albums that fall below the
               quality cutoff.
               <br />
+              <br />
               <b>Quality cutoff</b> — the minimum acceptable quality class: <code>1</code> = lossy,{" "}
               <code>2</code> = CD-lossless (FLAC 16/44.1), <code>3</code> = hi-res. An owned album is
               kept as-is when it’s ≥ the cutoff; otherwise a better copy is chased. Range 1–3.
               <br />
+              <br />
               <b>Poll interval</b> — hours between new-release checks. <b>Retry interval</b> — hours
               before re-attempting a release that couldn’t be found yet. <b>Upgrade window</b> — how
               many days after first acquiring an album to keep looking for a better copy.
-          </p>
+            </HelpButton>
+          </div>
           <div className="field-grid">
             {MONITOR_FIELDS.map(([key, label]) => (
               <label key={key} className="field">
@@ -379,18 +384,19 @@ export function SettingsForm() {
               />
               Scheduled discovery sweep
             </label>
-          </div>
-          <p className="help">
+            <HelpButton title="Discovery">
               When on, the worker periodically sweeps your followed artists for similar artists +
               their new releases (via ListenBrainz and, if configured, Last.fm) and lists them on{" "}
               <b>Discover</b>. Nothing is downloaded automatically — you Follow/Want from there.
               <br />
+              <br />
               <b>Interval</b> — hours between sweeps. <b>Seeds per chunk</b> — how many followed
               artists are processed per worker cycle (keeps job-claiming responsive on big rosters).
               <b> Similar per seed</b> — candidates pulled per artist. <b>Albums per artist</b> —
               releases surfaced per suggested artist. <b>Min score</b> — drops weak suggestions.{" "}
               <b>ListenBrainz base URL</b> — leave blank for the default endpoint.
-          </p>
+            </HelpButton>
+          </div>
           <div className="field-grid">
             {DISCOVERY_FIELDS.map(([key, label]) => (
               <label key={key} className="field">