fix(setup,ui): risolve errori setup + logo SVG theme-aware

- setup: corregge path templates (sibling di api/, non figlio) e firma TemplateResponse
- setup: invalida sessione client dopo operazioni che ruotano l'API key (init DB, creazione admin, cambio password, attivazione utente)
- api_client: include il nome del campo nei messaggi di errore 422 (FastAPI validation)
- ui: nuovo componente _app_logo.html (SVG inline theme-aware) usato su login e navbar

src/frontend/flask_app/templates/components/_app_logo.html

@@ -0,0 +1,35 @@
+<!--
+Inline TieMeasureFlow logo. Text fills use `currentColor`, so wrap with a
+parent that sets `color` (e.g. `text-slate-900 dark:text-white`) to make the
+wordmark adapt to the active theme. The caliper/flow icon keeps its brand
+blue regardless of theme.
+-->
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 260 48" fill="none"
+     class="{{ logo_class|default('h-10 w-auto') }}"
+     aria-label="TieMeasureFlow">
+  <!-- Caliper + flow icon (always brand color) -->
+  <g transform="translate(2, 6)">
+    <rect x="0" y="4" width="6" height="32" rx="1.5" fill="#2563EB"/>
+    <rect x="0" y="4" width="24" height="6" rx="1.5" fill="#2563EB"/>
+    <rect x="0" y="30" width="24" height="6" rx="1.5" fill="#2563EB"/>
+    <rect x="14" y="10" width="5" height="8" rx="1" fill="#1E40AF"/>
+    <rect x="14" y="22" width="5" height="8" rx="1" fill="#1E40AF"/>
+    <rect x="2" y="18" width="16" height="4" rx="1" fill="#3B82F6" opacity="0.6"/>
+    <rect x="7" y="7" width="1" height="3" rx="0.5" fill="#FFFFFF" opacity="0.7"/>
+    <rect x="10" y="7" width="1" height="3" rx="0.5" fill="#FFFFFF" opacity="0.7"/>
+    <rect x="13" y="7" width="1" height="3" rx="0.5" fill="#FFFFFF" opacity="0.7"/>
+    <rect x="16" y="7" width="1" height="3" rx="0.5" fill="#FFFFFF" opacity="0.7"/>
+    <rect x="19" y="7" width="1" height="3" rx="0.5" fill="#FFFFFF" opacity="0.7"/>
+    <path d="M26 20 C30 20, 32 14, 36 14 C40 14, 40 20, 36 20"
+          stroke="#2563EB" stroke-width="2.5" stroke-linecap="round" fill="none"/>
+    <path d="M34 17 L37 20 L34 23"
+          stroke="#2563EB" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" fill="none"/>
+  </g>
+
+  <!-- Wordmark: themed via currentColor; "Measure" stays brand-tinted -->
+  <g transform="translate(52, 0)" font-family="Inter, system-ui, sans-serif" letter-spacing="-0.5">
+    <text x="0"   y="34" font-size="28" font-weight="700" fill="currentColor">Tie</text>
+    <text x="44"  y="34" font-size="28" font-weight="500" fill="#2563EB">Measure</text>
+    <text x="166" y="34" font-size="28" font-weight="700" fill="currentColor">Flow</text>
+  </g>
+</svg>