refactor(cache): make CACHE_SCHEMA_VERSION private

It is only referenced within the module (by cache_schema_dir_name), so the
`pub` was unnecessary.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: wan9chi

crates/vite_task/src/session/cache/mod.rs

@@ -200,7 +200,7 @@ pub fn split_path(path: &str) -> (Option<&str>, &str) {
 /// its own cache warm across branch switches, and a cache from a different
 /// version is simply ignored (it lives in a directory this build never looks
 /// at) rather than aborting the run. Bumping the version starts a fresh cache.
-pub const CACHE_SCHEMA_VERSION: u32 = 13;
+const CACHE_SCHEMA_VERSION: u32 = 13;
 
 /// Name of the per-version subdirectory (e.g. `v13`) under the task-cache
 /// directory that holds the database and output archives for the current