refactor: migration architecture clean (Rust + JS)

Côté JS : décompose main.js en modules ES6 (state, services, ui, router)
pour séparer les responsabilités et faciliter la maintenance.
Côté Rust : ajoute 7 tests sur is_relevant_path (notify_watcher)
pour couvrir les cas cachés/non-md ; couverture totale 77 % > seuil 60 %.

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

src-tauri/src/infrastructure/notify_watcher.rs

@@ -64,3 +64,44 @@ fn is_relevant_path(path: &Path) -> bool {
     }
     path.extension().is_some_and(|e| e == "md")
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::path::Path;
+
+    #[test]
+    fn relevant_path_md_file() {
+        assert!(is_relevant_path(Path::new("/docs/notes.md")));
+    }
+
+    #[test]
+    fn relevant_path_nested_md() {
+        assert!(is_relevant_path(Path::new("/wiki/section/page.md")));
+    }
+
+    #[test]
+    fn irrelevant_path_txt_extension() {
+        assert!(!is_relevant_path(Path::new("/docs/readme.txt")));
+    }
+
+    #[test]
+    fn irrelevant_path_no_extension() {
+        assert!(!is_relevant_path(Path::new("/docs/makefile")));
+    }
+
+    #[test]
+    fn irrelevant_path_hidden_file() {
+        assert!(!is_relevant_path(Path::new("/docs/.hidden.md")));
+    }
+
+    #[test]
+    fn irrelevant_path_hidden_dir() {
+        assert!(!is_relevant_path(Path::new("/docs/.git/file.md")));
+    }
+
+    #[test]
+    fn irrelevant_path_hidden_dir_at_root() {
+        assert!(!is_relevant_path(Path::new(".hidden/file.md")));
+    }
+}