cc-sidepanel: bundle JetBrainsMono Nerd Font Mono (0.3.0)

The panel should match kitty's font, but extension pages can't reach system
fonts by name — CSP blocks `local()` — so the TTFs ship in the repo:

  fonts/JBMono-Regular.ttf  2.5MB  weight 400
  fonts/JBMono-Bold.ttf     2.5MB  weight 700

Copied from /usr/share/fonts/TTF/JetBrainsMonoNerdFontMono-{Regular,Bold}.ttf.
Heavy, but it's local-only — the panel never downloads them.

`@font-face` in sidepanel.html, fallback chain kept (ui-monospace, SF Mono,
Menlo, monospace). Line-height 1.4 -> 1.5 for JBMono's taller glyphs.

The Nerd Font variant means nerd-font glyphs leaking out of the pane render
properly instead of as boxes.

No `web_accessible_resources` needed: the side panel is an extension page on the
same chrome-extension:// origin, so bundled files are directly reachable. That
key is only for files injected into web pages.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

extension/sidepanel.html

@@ -4,10 +4,22 @@
 <meta charset="utf-8">
 <title>CC Sidepanel</title>
 <style>
+  @font-face {
+    font-family: "JBMono";
+    src: url("fonts/JBMono-Regular.ttf") format("truetype");
+    font-weight: 400;
+    font-style: normal;
+  }
+  @font-face {
+    font-family: "JBMono";
+    src: url("fonts/JBMono-Bold.ttf") format("truetype");
+    font-weight: 700;
+    font-style: normal;
+  }
   :root { color-scheme: dark; }
   body {
     margin: 0; padding: 10px; background: #16141c; color: #eae6f5;
-    font: 13px/1.4 ui-monospace, "SF Mono", Menlo, monospace;
+    font: 13px/1.5 "JBMono", ui-monospace, "SF Mono", Menlo, monospace;
     display: flex; flex-direction: column; height: 100vh; box-sizing: border-box;
   }
   select, textarea, button {