feat: migrate semantic search to pgvector + full-text search

Replace JSON-string embeddings with native pgvector(1536) storage and
add PostgreSQL full-text search (tsvector/GIN) with Reciprocal Rank Fusion
for hybrid keyword + semantic ranking.

Changes:
- NoteEmbedding.embedding: String → vector(1536) via pgvector
- NoteEmbedding: added updatedAt for reindex tracking
- Note: added tsv (tsvector) with auto-update trigger for FTS
- semantic-search.service: hybrid FTS + vector search with RRF fusion
- embedding.service: toVectorString() for pgvector SQL literals
- Removed JS-side cosine similarity loops (now DB-side via <=>)
- Added HNSW index on NoteEmbedding.embedding (cosine distance)
- Added GIN index on Note.tsv for FTS queries

Schema migration in: prisma/migrations/20260512120000_pgvector_and_fts_search/

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

architectural-grid10/src/components/settings/SettingsHeader.tsx

@@ -0,0 +1,51 @@
+import React from 'react';
+import { Settings, Sparkles, Palette, User, Database, Code, Info } from 'lucide-react';
+import { motion } from 'motion/react';
+import { SettingsTab } from '../../types';
+
+interface SettingsHeaderProps {
+  activeTab: SettingsTab;
+  setActiveTab: (tab: SettingsTab) => void;
+}
+
+export const SettingsHeader: React.FC<SettingsHeaderProps> = ({ activeTab, setActiveTab }) => {
+  const tabs = [
+    { id: 'general', label: 'Paramètres généraux', icon: <Settings size={14} /> },
+    { id: 'ai', label: 'Paramètres IA', icon: <Sparkles size={14} /> },
+    { id: 'appearance', label: 'Apparence', icon: <Palette size={14} /> },
+    { id: 'profile', label: 'Profil', icon: <User size={14} /> },
+    { id: 'data', label: 'Gestion des données', icon: <Database size={14} /> },
+    { id: 'mcp', label: 'Paramètres MCP', icon: <Code size={14} /> },
+    { id: 'about', label: 'À propos', icon: <Info size={14} /> },
+  ];
+
+  return (
+    <header className="px-12 pt-20 pb-16 space-y-12">
+      <div className="space-y-4">
+        <h1 className="text-[64px] font-serif text-ink tracking-tight leading-none italic font-medium">Paramètres</h1>
+        <p className="text-[10px] font-bold uppercase tracking-[0.4em] text-concrete opacity-60">Configuration & Préférences</p>
+      </div>
+
+      <nav className="flex items-center gap-1 border-b border-border/40 pb-px">
+        {tabs.map((tab) => (
+          <button
+            key={tab.id}
+            onClick={() => setActiveTab(tab.id as SettingsTab)}
+            className={`flex items-center gap-2.5 px-6 py-5 text-[10px] font-bold uppercase tracking-[0.18em] transition-all relative whitespace-nowrap
+              ${activeTab === tab.id ? 'text-ink' : 'text-concrete hover:text-ink/60'}`}
+          >
+            <span className={activeTab === tab.id ? 'text-ink' : 'text-concrete'}>{tab.icon}</span>
+            {tab.label}
+            {activeTab === tab.id && (
+              <motion.div 
+                layoutId="activeSettingsTabLine" 
+                className="absolute bottom-0 left-0 right-0 h-0.5 bg-ink" 
+                transition={{ type: 'spring', bounce: 0.1, duration: 0.8 }}
+              />
+            )}
+          </button>
+        ))}
+      </nav>
+    </header>
+  );
+};