chore(TRUEREF-0022): fix lint errors and update architecture docs

- Fix 15 ESLint errors across pipeline workers, SSE endpoints, and UI
- Replace explicit any with proper entity types in worker entries
- Remove unused imports and variables (basename, SSEEvent, getBroadcasterFn, seedRules)
- Use empty catch clauses instead of unused error variables
- Use SvelteSet for reactive Set state in repository page
- Fix operator precedence in nullish coalescing expression
- Replace $state+$effect with $derived for concurrency input
- Use resolve() directly in href for navigation lint rule
- Update ARCHITECTURE.md and FINDINGS.md for worker-thread architecture

src/routes/settings/+page.svelte

@@ -66,16 +66,12 @@
 	let saveError = $state<string | null>(null);
 	let saveStatusTimer: ReturnType<typeof setTimeout> | null = null;
 
-	let concurrencyInput = $state<number>(0);
+	let concurrencyInput = $derived(data.indexingConcurrency);
 	let concurrencySaving = $state(false);
 	let concurrencySaveStatus = $state<'idle' | 'ok' | 'error'>('idle');
 	let concurrencySaveError = $state<string | null>(null);
 	let concurrencySaveStatusTimer: ReturnType<typeof setTimeout> | null = null;
 
-	$effect(() => {
-		concurrencyInput = data.indexingConcurrency;
-	});
-
 	const currentSettings = $derived(settingsOverride ?? data.settings);
 	const activeProfile = $derived(currentSettings.activeProfile);
 	const activeConfigEntries = $derived(activeProfile?.configEntries ?? []);