feat(#82): implement Personality Module

- Add Personality model to Prisma schema with FormalityLevel enum
- Create migration and seed with 6 default personalities
- Implement CRUD API with TDD approach (97.67% coverage)
  * PersonalitiesService: findAll, findOne, findDefault, create, update, remove
  * PersonalitiesController: REST endpoints with auth guards
  * Comprehensive test coverage (21 passing tests)
- Add Personality types to shared package
- Create frontend components:
  * PersonalitySelector: dropdown for choosing personality
  * PersonalityPreview: preview personality style and system prompt
  * PersonalityForm: create/edit personalities with validation
  * Settings page: manage personalities with CRUD operations
- Integrate with Ollama API:
  * Support personalityId in chat endpoint
  * Auto-inject system prompt from personality
  * Fall back to default personality if not specified
- API client for frontend personality management

All tests passing with 97.67% backend coverage (exceeds 85% requirement)

apps/web/src/components/personalities/PersonalitySelector.tsx

@@ -0,0 +1,76 @@
+"use client";
+
+import { useState, useEffect } from "react";
+import type { Personality } from "@mosaic/shared";
+import { fetchPersonalities } from "@/lib/api/personalities";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
+import { Label } from "@/components/ui/label";
+import { Badge } from "@/components/ui/badge";
+
+interface PersonalitySelectorProps {
+  value?: string;
+  onChange?: (personalityId: string) => void;
+  label?: string;
+  className?: string;
+}
+
+export function PersonalitySelector({
+  value,
+  onChange,
+  label = "Select Personality",
+  className,
+}: PersonalitySelectorProps): JSX.Element {
+  const [personalities, setPersonalities] = useState<Personality[]>([]);
+  const [isLoading, setIsLoading] = useState<boolean>(true);
+
+  useEffect(() => {
+    loadPersonalities();
+  }, []);
+
+  async function loadPersonalities(): Promise<void> {
+    try {
+      setIsLoading(true);
+      const response = await fetchPersonalities();
+      setPersonalities(response.data);
+    } catch (err) {
+      console.error("Failed to load personalities:", err);
+    } finally {
+      setIsLoading(false);
+    }
+  }
+
+  return (
+    <div className={className}>
+      {label && (
+        <Label htmlFor="personality-select" className="mb-2">
+          {label}
+        </Label>
+      )}
+      <Select value={value} onValueChange={onChange} disabled={isLoading}>
+        <SelectTrigger id="personality-select">
+          <SelectValue placeholder={isLoading ? "Loading..." : "Choose a personality"} />
+        </SelectTrigger>
+        <SelectContent>
+          {personalities.map((personality) => (
+            <SelectItem key={personality.id} value={personality.id}>
+              <div className="flex items-center gap-2">
+                <span>{personality.name}</span>
+                {personality.isDefault && (
+                  <Badge variant="secondary" className="ml-2">
+                    Default
+                  </Badge>
+                )}
+              </div>
+            </SelectItem>
+          ))}
+        </SelectContent>
+      </Select>
+    </div>
+  );
+}