feat: structured artifact rendering, UX improvements

- Render structured artifacts from agent results with type-aware
  formatting: code blocks with syntax highlighting and copy button,
  terminal-style command output, search result cards, and text findings
- Make FinalResult panel collapsible (default collapsed) with scrollable
  content (max-h-96) to prevent dominating the chat view
- Add clickable URL detection in summaries and artifact content
- Fix code block contrast for both light and dark mode
- Animate progress bar with pulse ring on active step and gradient
  shimmer on connecting lines
- Fix tab-switching bug: use module-level orchestrationStore singleton
  so orchestration state survives route navigation
- Remove sample/demo data seeding and clean up persisted localStorage
  entries from previous sample sessions
- Remove showSampleBadge prop from PageHeader
- Regenerate proto types for new Artifact message and ArtifactType enum
- Update README project structure (remove deleted data/ directory)

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

src/lib/composables/useOrchestration.svelte.ts

@@ -6,7 +6,7 @@ import { OrchestrationState } from '$lib/proto/llm_multiverse/v1/orchestrator_pb
 import { sessionStore } from '$lib/stores/sessions.svelte';
 import { memoryStore } from '$lib/stores/memory.svelte';
 import { auditStore } from '$lib/stores/audit.svelte';
-import { toastStore } from '$lib/stores/toast.svelte';
+import { logger } from '$lib/utils/logger';
 
 export function createOrchestration() {
 	let isStreaming = $state(false);
@@ -57,6 +57,10 @@ export function createOrchestration() {
 
 				if (response.state !== lastAuditState) {
 					const stateLabel = OrchestrationState[response.state] ?? String(response.state);
+					logger.debug('useOrchestration', `State: ${stateLabel}`, {
+						sessionId,
+						state: response.state
+					});
 					auditStore.addEvent(sessionId, {
 						eventType: 'state_change',
 						details: response.message || `State changed to ${stateLabel}`,
@@ -88,21 +92,27 @@ export function createOrchestration() {
 				};
 			}
 		} catch (err) {
-			const friendlyMsg =
-				err instanceof OrchestratorError
-					? friendlyMessage(err.code)
-					: 'An unexpected error occurred';
-			error = friendlyMsg;
+			const isOrcErr = err instanceof OrchestratorError;
+			const code = isOrcErr ? err.code : 'unknown';
+			const details = isOrcErr ? err.details : undefined;
+			const friendlyMsg = isOrcErr
+				? friendlyMessage(err.code)
+				: 'An unexpected error occurred';
+			const displayMsg =
+				code && code !== 'unknown'
+					? `${friendlyMsg} (${code})`
+					: friendlyMsg;
+			error = displayMsg;
 			lastFailedContent = content;
-			toastStore.addToast({ message: friendlyMsg, type: 'error' });
+			logger.error('useOrchestration', 'Request failed', { code, details });
 			auditStore.addEvent(sessionId, {
 				eventType: 'error',
-				details: friendlyMsg
+				details: `${friendlyMsg} | code=${code}${details ? ` | details=${details}` : ''}`
 			});
 			const idx = messages.length - 1;
 			messages[idx] = {
 				...messages[idx],
-				content: `\u26A0 ${friendlyMsg}`
+				content: `\u26A0 ${displayMsg}`
 			};
 		} finally {
 			isStreaming = false;
@@ -149,3 +159,9 @@ export function createOrchestration() {
 		reset
 	};
 }
+
+/**
+ * Module-level singleton so orchestration state survives tab/route changes.
+ * The chat page uses this instead of calling createOrchestration() per mount.
+ */
+export const orchestrationStore = createOrchestration();