[feat](trx-frontend-http): add APRS symbols, map links, and correlation demodulator

- Add APRS symbol icons using hessu/aprs-symbols sprite sheets
- Parse uncompressed and compressed position formats for lat/lon
- Render clickable OpenStreetMap links for position packets
- Replace delay-and-multiply discriminator with mark/space correlation
  detector for more robust AFSK decoding
- Reduce PLL gain from 0.7 to 0.4 for stable clock recovery
- Move plugin JS files to plugins/ subdirectory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -218,6 +218,9 @@ small { color: var(--text-muted); }
 .aprs-packet:last-child { border-bottom: none; }
 .aprs-call { color: var(--accent-green); font-weight: 600; }
 .aprs-time { color: var(--text-muted); margin-right: 0.5rem; }
+.aprs-symbol { display: inline-block; width: 24px; height: 24px; background-size: 384px 192px; vertical-align: middle; margin-right: 0.3rem; }
+.aprs-pos { color: var(--accent-green); text-decoration: none; margin-left: 0.3rem; font-size: 0.8rem; }
+.aprs-pos:hover { text-decoration: underline; }
 
 .cw-controls { display: flex; gap: 0.6rem; align-items: center; margin-bottom: 0.75rem; }
 .cw-config { display: flex; gap: 1rem; align-items: flex-end; flex-wrap: wrap; margin-bottom: 0.75rem; }