feat(infra): add ServerState, MongoDB, auth middleware, and DaisyUI theme toggle

Introduce centralized ServerState (Arc-wrapped, Box::leaked configs) loaded
once at startup, replacing per-request dotenvy/env::var calls across all
server functions. Add MongoDB Database wrapper with connection pooling.
Add tower middleware that gates all /api/ server function endpoints behind
session authentication (401 for unauthenticated callers, except check-auth).
Fix DaisyUI theme toggle to use certifai-dark/certifai-light theme names
and replace hardcoded hex colors in main.css with CSS variables.

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

src/infrastructure/llm.rs

@@ -166,19 +166,20 @@ pub async fn summarize_article(
     ollama_url: String,
     model: String,
 ) -> Result<String, ServerFnError> {
-    dotenvy::dotenv().ok();
     use inner::{fetch_article_text, ChatMessage, OllamaChatRequest, OllamaChatResponse};
 
-    // Fall back to env var or default if the URL is empty
+    let state: crate::infrastructure::ServerState =
+        dioxus_fullstack::FullstackContext::extract().await?;
+
+    // Use caller-provided values or fall back to ServerState config
     let base_url = if ollama_url.is_empty() {
-        std::env::var("OLLAMA_URL").unwrap_or_else(|_| "http://localhost:11434".into())
+        state.services.ollama_url.clone()
     } else {
         ollama_url
     };
 
-    // Fall back to env var or default if the model is empty
     let model = if model.is_empty() {
-        std::env::var("OLLAMA_MODEL").unwrap_or_else(|_| "llama3.1:8b".into())
+        state.services.ollama_model.clone()
     } else {
         model
     };
@@ -264,17 +265,19 @@ pub async fn chat_followup(
     ollama_url: String,
     model: String,
 ) -> Result<String, ServerFnError> {
-    dotenvy::dotenv().ok();
     use inner::{ChatMessage, OllamaChatRequest, OllamaChatResponse};
 
+    let state: crate::infrastructure::ServerState =
+        dioxus_fullstack::FullstackContext::extract().await?;
+
     let base_url = if ollama_url.is_empty() {
-        std::env::var("OLLAMA_URL").unwrap_or_else(|_| "http://localhost:11434".into())
+        state.services.ollama_url.clone()
     } else {
         ollama_url
     };
 
     let model = if model.is_empty() {
-        std::env::var("OLLAMA_MODEL").unwrap_or_else(|_| "llama3.1:8b".into())
+        state.services.ollama_model.clone()
     } else {
         model
     };