fix(dashboard): JSON config renderizzato come HTML colorato custom (no Prism/hljs)

Soluzione robusta al bug "chiavi JSON invisibili": invece di tentare
override CSS su Prism.js/highlight.js (che nelle build NiceGUI possono
non essere attivi o variare), il JSON viene serializzato server-side con
span colorati espliciti e renderizzato via ui.html.

Implementato helper _json_to_html(obj) che produce HTML con classi:
- .cb-key (chiavi)   → cyan #00D9FF
- .cb-string         → green #00E676
- .cb-number         → pink  #FF2D87
- .cb-bool / .cb-null → amber #FFB800
- .cb-punct (graffe, virgole, due punti) → muted

Stessa logica per system_prompt e raw LLM output in /genomes: sostituito
ui.code(language=text) con ui.html('<pre class="raw-block">') e
html.escape() per safety XSS. Background dedicato #1A1A24 e font
JetBrains Mono 13.5px, line-height 1.7, ottimo contrasto su qualsiasi
browser senza dipendere da syntax highlighter esterno.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/multi_swarm/dashboard/nicegui_app.py

@@ -18,6 +18,7 @@ Palette "Neon Trading Dashboard" (ispirata screenshot 2026-05-11):
 
 from __future__ import annotations
 
+import html
 import json
 import os
 from pathlib import Path
@@ -269,10 +270,78 @@ pre[class*="language-"], code[class*="language-"] {{
 }}
 
 .q-badge {{ border-radius: 6px !important; font-weight: 500 !important; padding: 4px 10px !important; font-size: 12px !important; }}
+
+.config-block {{
+    background: #1A1A24;
+    color: {COLOR_TEXT};
+    border: 1px solid {COLOR_BORDER};
+    border-radius: 10px;
+    padding: 18px 20px;
+    font-family: 'JetBrains Mono', 'Fira Code', monospace;
+    font-size: 13.5px;
+    line-height: 1.7;
+    overflow-x: auto;
+    white-space: pre;
+    margin: 0;
+}}
+.config-block .cb-key {{ color: {COLOR_SECONDARY}; font-weight: 500; }}
+.config-block .cb-string {{ color: {COLOR_SUCCESS}; }}
+.config-block .cb-number {{ color: {COLOR_PRIMARY}; font-weight: 500; }}
+.config-block .cb-bool {{ color: {COLOR_ACCENT}; }}
+.config-block .cb-null {{ color: {COLOR_ACCENT}; font-style: italic; }}
+.config-block .cb-punct {{ color: {COLOR_TEXT_MUTED}; }}
+
+.raw-block {{
+    background: #1A1A24;
+    color: {COLOR_TEXT};
+    border: 1px solid {COLOR_BORDER};
+    border-radius: 10px;
+    padding: 18px 20px;
+    font-family: 'JetBrains Mono', 'Fira Code', monospace;
+    font-size: 13px;
+    line-height: 1.6;
+    overflow-x: auto;
+    white-space: pre-wrap;
+    word-break: break-word;
+    max-height: 400px;
+    overflow-y: auto;
+    margin: 0;
+}}
 </style>
 """
 
 
+def _json_to_html(obj: Any, indent: int = 0) -> str:
+    """Render JSON con span colorati espliciti. Garantisce leggibilità ovunque."""
+    pad = "  " * indent
+    inner_pad = "  " * (indent + 1)
+    if isinstance(obj, dict):
+        if not obj:
+            return '<span class="cb-punct">{}</span>'
+        items = []
+        for k, v in obj.items():
+            key = f'<span class="cb-key">"{html.escape(str(k))}"</span>'
+            val = _json_to_html(v, indent + 1)
+            items.append(f"{inner_pad}{key}<span class=\"cb-punct\">:</span> {val}")
+        return ('<span class="cb-punct">{</span>\n'
+                + '<span class="cb-punct">,</span>\n'.join(items)
+                + f'\n{pad}<span class="cb-punct">}}</span>')
+    if isinstance(obj, list):
+        if not obj:
+            return '<span class="cb-punct">[]</span>'
+        items = [_json_to_html(x, indent + 1) for x in obj]
+        return ('<span class="cb-punct">[</span>\n'
+                + '<span class="cb-punct">,</span>\n'.join(inner_pad + i for i in items)
+                + f'\n{pad}<span class="cb-punct">]</span>')
+    if isinstance(obj, bool):
+        return f'<span class="cb-bool">{str(obj).lower()}</span>'
+    if obj is None:
+        return '<span class="cb-null">null</span>'
+    if isinstance(obj, (int, float)):
+        return f'<span class="cb-number">{obj}</span>'
+    return f'<span class="cb-string">"{html.escape(str(obj))}"</span>'
+
+
 def _apply_theme() -> None:
     ui.add_head_html(_CUSTOM_CSS)
     ui.dark_mode().enable()
@@ -486,7 +555,7 @@ def index() -> None:
         completed_lbl = ui.label("Completed: —")
     ui.separator()
     ui.label("Config").classes("text-subtitle1")
-    cfg_code = ui.code("", language="json").classes("w-full")
+    cfg_code = ui.html('<pre class="config-block"></pre>').classes("w-full")
 
     def refresh() -> None:
         run_id = select.value
@@ -518,7 +587,7 @@ def index() -> None:
 
         started_lbl.text = f"Started: {s['started_at']}"
         completed_lbl.text = f"Completed: {s['completed_at']}"
-        cfg_code.content = json.dumps(s["config"], indent=2)
+        cfg_code.content = f'<pre class="config-block">{_json_to_html(s["config"])}</pre>'
 
     def on_select_change() -> None:
         state["run_id"] = select.value
@@ -688,10 +757,10 @@ def genomes() -> None:
                 style_lbl = ui.label("—").classes("text-h4")
 
         ui.label("System prompt").classes("text-subtitle1 q-mt-md")
-        prompt_code = ui.code("—", language="text").classes("w-full")
+        prompt_code = ui.html('<pre class="raw-block">—</pre>').classes("w-full")
 
         ui.label("Raw LLM output").classes("text-subtitle1 q-mt-md")
-        raw_code = ui.code("—", language="text").classes("w-full")
+        raw_code = ui.html('<pre class="raw-block">—</pre>').classes("w-full")
 
         parse_error_lbl = ui.label("").classes("q-mt-sm").style(
             "color: #FF6B6B; font-weight: 600;"
@@ -705,8 +774,12 @@ def genomes() -> None:
         dd_lbl.text = f"{float(row.get('max_dd', 0)):.3f}"
         trades_lbl.text = str(int(row.get("n_trades", 0)))
         style_lbl.text = str(row.get("cognitive_style", "—"))
-        prompt_code.content = str(row.get("system_prompt", "—"))
-        raw_code.content = str(row.get("raw_text", "—") or "—")
+        prompt_code.content = (
+            f'<pre class="raw-block">{html.escape(str(row.get("system_prompt", "—")))}</pre>'
+        )
+        raw_code.content = (
+            f'<pre class="raw-block">{html.escape(str(row.get("raw_text", "—") or "—"))}</pre>'
+        )
         pe = row.get("parse_error")
         parse_error_lbl.text = f"❌ Parse error: {pe}" if pe else ""