refactor(ui): simplify AppSwitcher styles and migrate to local SVG icons

- Replace complex gradient animations with clean, minimal tab design
- Migrate from @lobehub/icons CDN to local SVG assets for better reliability
- Fix clippy warning in error.rs (use inline format args)
- Improve code formatting in skill service and commands
- Reduce CSS complexity in AppSwitcher component (removed blur effects and gradients)
- Update BrandIcons to use imported local SVG files instead of dynamic image loading

This improves performance, reduces external dependencies, and provides a cleaner UI experience.

src-tauri/src/commands/skill.rs

@@ -56,26 +56,20 @@ pub async fn install_skill(
 
     if !skill.installed {
         let repo = SkillRepo {
-            owner: skill
-                .repo_owner
-                .clone()
-                .ok_or_else(|| {
-                    format_skill_error(
-                        "MISSING_REPO_INFO",
-                        &[("directory", &directory), ("field", "owner")],
-                        None,
-                    )
-                })?,
-            name: skill
-                .repo_name
-                .clone()
-                .ok_or_else(|| {
-                    format_skill_error(
-                        "MISSING_REPO_INFO",
-                        &[("directory", &directory), ("field", "name")],
-                        None,
-                    )
-                })?,
+            owner: skill.repo_owner.clone().ok_or_else(|| {
+                format_skill_error(
+                    "MISSING_REPO_INFO",
+                    &[("directory", &directory), ("field", "owner")],
+                    None,
+                )
+            })?,
+            name: skill.repo_name.clone().ok_or_else(|| {
+                format_skill_error(
+                    "MISSING_REPO_INFO",
+                    &[("directory", &directory), ("field", "name")],
+                    None,
+                )
+            })?,
             branch: skill
                 .repo_branch
                 .clone()