Add stats, profiles, avatars and palaute

Step 6. The surfaces around the review loop.

- Nine leaderboards, ordered and limited in SQL, each with a deterministic
  tie-break so a tied board doesn't reshuffle between reloads. Min 3 reviews
  to qualify, for reviewer boards too
- Profiles show counts and history-wide averages and the member's songs,
  never a list of their reviews — per-song opinion stays gated
- Avatars: 5MB in, 256px JPEG out, ffmpeg's re-encode being the validation.
  No upload still means initials, and avatars are public
- Changing your own password requires the current one and drops your other
  sessions
- Palaute: free text plus the page you were on, carried in a footer link, and
  the user agent from the header. Reporters see their own; the admin resolves
  them with a timestamp rather than a status enum
- Admin gained the song list with delete, the reports page, and an open-report
  count on the dashboard

Two theme fixes the screenshots caught: leaderboard ranks need a CSS counter
because display:grid suppresses list markers, and count-based boards were
printing 3.0 where they mean 3.

templates/report.html

@@ -0,0 +1,30 @@
+{{define "content"}}
+<h1>Palaute</h1>
+<p class="muted">Kerro mikä on rikki tai ärsyttää. Ei kategorioita eikä prioriteetteja — yksi
+  virke riittää.</p>
+
+<form method="post" action="/report" class="stack">
+  <input type="hidden" name="from" value="{{.Data.From}}">
+  <label>Palaute
+    <textarea name="body" rows="6" maxlength="2000" required autofocus
+              placeholder="Esim. soitin ei toimi puhelimella."></textarea>
+  </label>
+  <button type="submit">Lähetä palaute</button>
+</form>
+<p class="muted small">Lähetämme mukaan sivun, jolla olit ({{.Data.From}}), sekä selaimen tiedot.</p>
+
+{{with .Data.Mine}}
+<section>
+  <h2>Omat palautteet</h2>
+  {{range .}}
+    <article class="review{{if .Open}} own{{end}}">
+      <header>
+        <span class="badge {{if .Open}}pending{{else}}reviewed{{end}}">{{if .Open}}avoin{{else}}käsitelty{{end}}</span>
+        <span class="meta">{{fidate .CreatedAt}}{{if .Page}} · {{.Page}}{{end}}</span>
+      </header>
+      <p>{{.Body}}</p>
+    </article>
+  {{end}}
+</section>
+{{end}}
+{{end}}