refactor: reorganize file operations and extract test modules

- Extract mover and undo functionality into dedicated modules (mover/ and undo/ subdirectories)
- Move cross-platform file operations to separate file_ops.rs module for reusability
- Extract batch and categorizer tests into separate test files (batch_test.rs, categorizer_test.rs)
- Refactor orchestrator.rs with extracted helper functions for improved readability
  - Separate cache and undo log initialization
  - Extract path resolution and offline mode determination logic
  - Simplify main organization flow by delegating to helper functions
- Update module exports to expose new types and functions (MoveError, MoveSummary, UndoError, UndoSummary)
- Reduce code duplication of move_file_cross_platform implementation

src/files/mover/display.rs

@@ -0,0 +1,43 @@
+use crate::models::FileCategory;
+use colored::*;
+use std::path::MAIN_SEPARATOR;
+
+pub(super) fn display_plan(files: &[FileCategory]) {
+    println!("\n{}", "--- EXECUTION PLAN ---".bold().underline());
+
+    if files.is_empty() {
+        println!("{}", "No files to organize.".yellow());
+        return;
+    }
+
+    for item in files {
+        let target_display = format_target_path(&item.category, &item.sub_category);
+        println!(
+            "Plan: {} -> {}{}",
+            item.filename, target_display, MAIN_SEPARATOR
+        );
+    }
+}
+
+pub(super) fn print_summary(summary: &super::types::MoveSummary) {
+    println!("\n{}", "Organization Complete!".bold().green());
+    println!(
+        "Files moved: {}, Errors: {}",
+        summary.moved_count().to_string().green(),
+        summary.error_count().to_string().red()
+    );
+}
+
+pub(super) fn format_target_path(category: &str, sub_category: &str) -> String {
+    let target_display = format!("{}", category.green());
+    if sub_category.is_empty() {
+        target_display
+    } else {
+        format!(
+            "{}{}{}",
+            target_display,
+            MAIN_SEPARATOR,
+            sub_category.blue()
+        )
+    }
+}