feat: convert to argument.es — Spanish, vote buttons, Docker

- Translate all ~430 prompts to Spanish with cultural adaptations
- Translate all UI strings (frontend, admin, history, broadcast)
- Translate AI system prompts; models now respond in Spanish
- Replace Twitch/Fossabot viewer voting with in-site vote buttons
- Add POST /api/vote endpoint (IP-based, supports vote switching)
- Vote buttons appear during voting phase with active state highlight
- Rename project to argument.es throughout (package.json, cookie, DB)
- Add docker-compose.yml with SQLite volume mount
- Add .env.sample documenting all required and optional vars

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend.css

@@ -138,8 +138,14 @@ body {
   color: var(--text-dim);
 }
 
-.vote-hint {
+.vote-panel {
   margin: -10px 0 22px;
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.vote-panel__label {
   font-family: var(--mono);
   font-size: 11px;
   letter-spacing: 0.5px;
@@ -147,8 +153,40 @@ body {
   color: var(--text-muted);
 }
 
-.vote-hint strong {
+.vote-panel__buttons {
+  display: flex;
+  gap: 10px;
+}
+
+.vote-btn {
+  flex: 1;
+  padding: 10px 16px;
+  background: var(--surface);
+  border: 1px solid var(--border);
+  border-radius: 8px;
   color: var(--text);
+  cursor: pointer;
+  font-family: var(--sans);
+  font-size: 13px;
+  transition: border-color 0.15s, background 0.15s;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 6px;
+}
+
+.vote-btn:hover {
+  border-color: #444;
+  background: #1a1a1a;
+}
+
+.vote-btn--active {
+  border-color: var(--accent);
+  background: rgba(217, 119, 87, 0.12);
+}
+
+.vote-btn--active:hover {
+  background: rgba(217, 119, 87, 0.18);
 }
 
 /* ── Prompt ───────────────────────────────────────────────────── */