✨ feat(llm-playground): add model metadata system and SSD documentation

- Add MODEL_METADATA config for Ollama models with descriptions and modality
- Update default model to gemma3:4b
- Show model descriptions in ModelSelector and ComparisonSelector
- Add docs/OLLAMA_MODELS.md with instructions for adding new models
- Document external 4TB SSD setup in MAC_MINI_SERVER.md
- Add gemma3:12b, gemma3:27b, qwen2.5-coder:14b to model registry

services/llm-playground/src/lib/components/comparison/ModelComparisonSelector.svelte

@@ -42,6 +42,7 @@
 					class="flex cursor-pointer items-center gap-2 rounded p-2 transition-colors hover:bg-zinc-800"
 					class:opacity-50={isDisabled}
 					class:cursor-not-allowed={isDisabled}
+					title={model.description || ''}
 				>
 					<input
 						type="checkbox"
@@ -50,9 +51,16 @@
 						disabled={isDisabled}
 						class="rounded"
 					/>
-					<span class="truncate text-sm" style="color: var(--color-text);">
-						{getModelDisplayName(model.id)}
-					</span>
+					<div class="min-w-0 flex-1">
+						<span class="block truncate text-sm" style="color: var(--color-text);">
+							{getModelDisplayName(model.id)}
+						</span>
+						{#if model.description}
+							<span class="block truncate text-xs" style="color: var(--color-text-muted);">
+								{model.description}
+							</span>
+						{/if}
+					</div>
 				</label>
 			{/each}
 		</div>

services/llm-playground/src/lib/components/settings/ModelSelector.svelte

@@ -1,11 +1,19 @@
 <script lang="ts">
-	import { modelsStore } from '$lib/stores/models.svelte';
+	import { modelsStore, MODEL_METADATA } from '$lib/stores/models.svelte';
 	import { settingsStore } from '$lib/stores/settings.svelte';
 	import { onMount } from 'svelte';
 
 	onMount(() => {
 		modelsStore.loadModels();
 	});
+
+	// Get description for currently selected model
+	const selectedModelDescription = $derived(() => {
+		const modelName = settingsStore.model.includes('/')
+			? settingsStore.model.split('/').slice(1).join('/')
+			: settingsStore.model;
+		return MODEL_METADATA[modelName]?.description;
+	});
 </script>
 
 <div>
@@ -48,8 +56,11 @@
 				</optgroup>
 			{/each}
 		</select>
-		<p class="mt-1.5 text-xs" style="color: var(--color-text-muted);">
-			{modelsStore.models.length} models available
-		</p>
+		<div class="mt-1.5 text-xs" style="color: var(--color-text-muted);">
+			{#if selectedModelDescription()}
+				<p class="mb-0.5">{selectedModelDescription()}</p>
+			{/if}
+			<p>{modelsStore.models.length} models available</p>
+		</div>
 	{/if}
 </div>