fix: handle 404 gracefully for admin config endpoint

- loadConfig now uses default values when config file doesn't exist (404)
- No error shown to user when config file is missing
- Config tab loads with empty defaults instead of error message

src/views/AdminView.vue

@@ -1296,6 +1296,17 @@ async function loadConfig() {
   configError.value = ''
   try {
     const res = await fetch('/api/v1/admin/config')
+    if (res.status === 404) {
+      // Config file doesn't exist yet, use defaults
+      vlmPrompts.value = {}
+      llmConfig.value = {}
+      processorConfig.value = {}
+      filterConfig.value = {}
+      systemConfig.value = {}
+      searchConfig.value = { vlm_min_score: 0.0, vlm_max_results: 5, vlm_output_language: 'en' }
+      pipelineConfig.value = { enabled: false, max_concurrent_stages: 3, default_timeout_secs: 3600 }
+      return
+    }
     if (!res.ok) throw new Error(`HTTP ${res.status}`)
     const data = await res.json()
     vlmPrompts.value = data.vlm_prompts || {}