feat: add File.glob for file pattern matching (issue 15)

Add File.glob(pattern) effect operation that returns a list of file
paths matching a glob pattern (e.g., "src/**/*.lux"). Implemented
across interpreter (using glob crate), JS backend (handler-based),
and C backend (using POSIX glob.h).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Cargo.toml

@@ -17,6 +17,7 @@ reqwest = { version = "0.11", default-features = false, features = ["blocking",
 tiny_http = "0.12"
 rusqlite = { version = "0.31", features = ["bundled"] }
 postgres = "0.19"
+glob = "0.3"
 
 
 [dev-dependencies]