feat(call): mic level meter on the mute button (#146)

While unmuted, the microphone button (call view and the bottom call bar)
shows three small green bars in the icon's corner driven by the fork's
io.lotus.mic_level (element-call v0.25.0-lotus.16), so you can see the mic is
actually picking you up. Nothing is drawn while muted or silent; the button's
label is unchanged (the bars are decorative).

Your own name no longer appears in the "… is speaking" line: that is now for
everyone else, and your voice is on the meter. Avatar speaking rings still
include you, and the "You're muted" talking-while-muted notice is unchanged.

Verified in a local call with a fake-tone mic: data-mic-level cycles 3/2/1
with the tone on both buttons, disappears on mute and returns on unmute; the
status line reads "bob is speaking..." only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/features/call/MicLevelBars.tsx

@@ -0,0 +1,45 @@
+import React from 'react';
+import { color } from 'folds';
+
+type MicLevelBarsProps = {
+  /** 0–3; nothing is drawn at 0. */
+  level: number;
+};
+
+const HEIGHTS = [3, 5, 7];
+
+/**
+ * [Gitea #146] Three small bars in the corner of the mic button showing your
+ * own input level while unmuted, so you can see the mic is actually picking
+ * you up. Decorative: the button's label already says whether it's on.
+ */
+export function MicLevelBars({ level }: MicLevelBarsProps) {
+  if (level <= 0) return null;
+  return (
+    <span
+      aria-hidden
+      data-mic-level={level}
+      style={{
+        position: 'absolute',
+        right: 1,
+        bottom: 1,
+        display: 'flex',
+        alignItems: 'flex-end',
+        gap: 1,
+        pointerEvents: 'none',
+      }}
+    >
+      {HEIGHTS.map((h, i) => (
+        <span
+          key={h}
+          style={{
+            width: 2,
+            height: h,
+            borderRadius: 1,
+            background: i < level ? color.Success.Main : 'transparent',
+          }}
+        />
+      ))}
+    </span>
+  );
+}