Refactor FileCache to use Condvar for efficient waits

The `FileCache` now uses `std::sync::Condvar` to signal when files have
finished loading. This replaces the previous spin-wait mechanism,
significantly improving efficiency by allowing waiting threads to sleep
until explicitly woken up.

The `wait_for_load` method now blocks on the `Condvar`, and the
`insert_m1` and `insert_tick` methods call `notify_all` after updating
the cache and removing the loading guard. This ensures that all waiting
threads are woken up and can re-check the cache.

Additionally, `ensure_m1_loaded` and `ensure_tick_loaded` in
`DataServer` have been simplified to directly call `wait_for_load` when
another thread is already loading the file, removing the redundant
synchronous loading logic.
Refactor FileCache to use Condvar

src/bin/ast.rs

@@ -53,11 +53,22 @@ struct Cli {
     /// Emit the parsed source back as Myc code (round-trip test)
     #[arg(long)]
     emit: bool,
+
+    /// Path to tick data directory (overrides default /mnt/tickdata/Pepperstone)
+    #[arg(long)]
+    data_path: Option<PathBuf>,
 }
 
 fn main() {
     let cli = Cli::parse();
 
+    // Initialize data server (before Environment::new so RTL has access)
+    if let Some(path) = &cli.data_path {
+        myc::ast::data_server::init_data_server(path);
+    } else {
+        myc::ast::data_server::init_default_data_server();
+    }
+
     if cli.mcp {
         if let Err(e) = myc::ast::mcp_server::run() {
             eprintln!("MCP server error: {}", e);