feat: add icon picker for tags with Iconify integration

- Add icon field to tag creation/update API and handlers
- Install @iconify packages (json, types, utils) as production deps
- Build IconPicker component for tag admin UI
- Fix apiFetch lazy initialization for build-time safety
- Update Docker to install production dependencies for SSR runtime

src/handlers/mod.rs

@@ -19,6 +19,7 @@ pub use tags::*;
 pub struct CreateTagRequest {
     pub name: String,
     pub slug: Option<String>,
+    pub icon: Option<String>,
     pub color: Option<String>,
 }
 
@@ -26,6 +27,7 @@ pub struct CreateTagRequest {
 pub struct UpdateTagRequest {
     pub name: String,
     pub slug: Option<String>,
+    pub icon: Option<String>,
     pub color: Option<String>,
 }
 

src/handlers/tags.rs

@@ -73,7 +73,7 @@ pub async fn create_tag_handler(
         &state.pool,
         &payload.name,
         payload.slug.as_deref(),
-        None, // icon - not yet supported in admin UI
+        payload.icon.as_deref(),
         payload.color.as_deref(),
     )
     .await
@@ -214,7 +214,7 @@ pub async fn update_tag_handler(
         tag.id,
         &payload.name,
         payload.slug.as_deref(),
-        None, // icon - not yet supported in admin UI
+        payload.icon.as_deref(),
         payload.color.as_deref(),
     )
     .await