fix(linux): prevent segfaults during rapid module reloads

Fixes multiple issues causing segfaults when hot-reloading modules
on Linux, particularly when file changes are detected rapidly:

- Enable is_file_ready() check on Linux to prevent loading partially-written
  shared libraries (previously only used on Windows/BSD)
- Fix event deduplication on Linux to actually remove duplicate inotify events
  instead of just marking them, preventing double-free on same module
- Reorder reload operations to unload old module only after successfully
  copying new version, avoiding invalid state when copy fails

Changes:
- platform.c: Remove __linux__ guards around is_file_ready() function
- platform.c: Add compaction step after deduplication to remove -1 entries
- stk.c: Move module unload to after platform_copy_file() in reload loop

These changes make Linux hot-reload as robust as Windows/BSD implementations.

src/stk.c

@@ -242,9 +242,6 @@ begin_operations:
 	for (i = 0; i < unload_count; ++i)
 		stk_module_unload(unloaded_mod_indices[i]);
 
-	for (i = 0; i < reload_count; ++i)
-		stk_module_unload(reloaded_mod_indices[i]);
-
 	for (i = 0; i < reload_count; ++i) {
 		int file_index = reloaded_mod_file_indices[i];
 		int mod_index = reloaded_mod_indices[i];
@@ -261,6 +258,8 @@ begin_operations:
 			continue;
 		}
 
+		stk_module_unload(mod_index);
+
 		load_result = stk_module_load(tmp_path, mod_index);
 		if (load_result != STK_MOD_INIT_SUCCESS) {
 			stk_log(stderr, "Failed to reload module %s: %s",