feat(EMBEDDINGS-0001): enable local embedder by default and overhaul settings page

- Wire local embedding provider as the default on startup when no profile is configured
- Refactor embedding settings into dedicated service, DTOs, mappers and models
- Rebuild settings page with profile management UI and live test feedback
- Expose index summary (indexed versions + embedding count) on repo endpoints
- Harden indexing pipeline and context search with additional test coverage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/server/mappers/embedding-profile.mapper.ts

@@ -0,0 +1,38 @@
+import {
+	EmbeddingProfile,
+	EmbeddingProfileEntity
+} from '$lib/server/models/embedding-profile.js';
+
+function parseConfig(config: Record<string, unknown> | string | null): Record<string, unknown> {
+	if (!config) {
+		return {};
+	}
+
+	if (typeof config === 'string') {
+		try {
+			const parsed = JSON.parse(config);
+			return parsed && typeof parsed === 'object' ? (parsed as Record<string, unknown>) : {};
+		} catch {
+			return {};
+		}
+	}
+
+	return config;
+}
+
+export class EmbeddingProfileMapper {
+	static fromEntity(entity: EmbeddingProfileEntity): EmbeddingProfile {
+		return new EmbeddingProfile({
+			id: entity.id,
+			providerKind: entity.provider_kind,
+			title: entity.title,
+			enabled: Boolean(entity.enabled),
+			isDefault: Boolean(entity.is_default),
+			model: entity.model,
+			dimensions: entity.dimensions,
+			config: parseConfig(entity.config),
+			createdAt: entity.created_at,
+			updatedAt: entity.updated_at
+		});
+	}
+}