refactor(odin): port check command.

cmd_check.odin

@@ -0,0 +1,79 @@
+package main
+
+import "core:fmt"
+import "core:os"
+import "core:path/filepath"
+import "core:strings"
+
+cmd_check :: proc(cmd: ^Command) {
+    check_path: string
+    if len(cmd.args) > 0 {
+        check_path = cmd.args[0]
+    } else {
+        cwd, cwd_err := os.get_working_directory(context.allocator)
+        if cwd_err != nil {
+            fmt.printf("Error getting current directory: %v\n", cwd_err)
+            return
+        }
+        check_path = cwd
+    }
+
+    abs_path: string
+    if filepath.is_abs(check_path) {
+        abs_path = check_path
+    } else {
+        resolved, abs_err := filepath.abs(check_path)
+        if abs_err != nil {
+            fmt.printf("Error getting absolute path: %v\n", abs_err)
+            return
+        }
+        abs_path = resolved
+    }
+
+    db, db_ok := db_open()
+    if !db_ok {
+        return
+    }
+    defer db_close(&db)
+
+    is_dir := os.is_directory(abs_path)
+
+    files_in_path: [dynamic]string
+
+    if is_dir {
+        if !can_scan() {
+            fmt.println("Error: please install fd to use the check command (https://github.com/sharkdp/fd)")
+            return
+        }
+
+        scanned, scan_ok := scan_path(abs_path, db.cfg)
+        if !scan_ok {
+            fmt.println("Error scanning directory for .env files")
+            return
+        }
+        files_in_path = scanned
+    } else {
+        append(&files_in_path, abs_path)
+    }
+
+    db_files, list_ok := db_list(&db)
+    if !list_ok {
+        return
+    }
+
+    not_backed := find_unbacked(files_in_path[:], db_files[:])
+
+    if len(not_backed) == 0 {
+        if len(files_in_path) == 0 {
+            fmt.println("No .env files found in the specified directory.")
+        } else {
+            fmt.println("✓ All .env files in the directory are backed up.")
+        }
+    } else {
+        fmt.printf("Found %d .env file(s) that are not backed up:\n", len(not_backed))
+        for file in not_backed {
+            fmt.printf("  %s\n", file)
+        }
+        fmt.println("\nRun 'envr sync' to back up these files.")
+    }
+}