feat: add async/await keywords, Num/String extensions, and Jinja markdown example

Add `async` and `await` token support to the Wren compiler with scheduler resolution logic, extend `Num` with `e` constant, hyperbolic trig, base conversion, and new methods (`isZero`, `gcd`, `lcm`, `digits`, etc.), extend `String` with `lower`, `upper`, `capitalize`, `title`, and regenerate `wren_core.wren.inc`. Include `Makefile` for multi-platform builds, rewrite `README.md` with updated build instructions, and add `example/await_demo.wren` and `example/jinja_markdown.wren` demonstrating new features.

example/tempfile_demo.wren

@@ -0,0 +1,60 @@
+// retoor <retoor@molodetz.nl>
+
+import "tempfile" for TempFile, NamedTemporaryFile, TemporaryDirectory
+import "pathlib" for Path
+
+System.print("=== TempFile Module Demo ===\n")
+
+System.print("--- Utility Functions ---")
+System.print("Temp directory: %(TempFile.gettempdir())")
+System.print("Temp prefix: %(TempFile.gettempprefix())")
+
+System.print("\n--- mktemp (name only, no file created) ---")
+var name = TempFile.mktemp(".txt", "demo_")
+System.print("Generated name: %(name)")
+System.print("File exists: %(Path.new(name).exists())")
+
+System.print("\n--- mkstemp (creates file atomically) ---")
+var path = TempFile.mkstemp(".dat", "demo_")
+System.print("Created file: %(path)")
+System.print("File exists: %(Path.new(path).exists())")
+Path.new(path).unlink()
+
+System.print("\n--- mkdtemp (creates directory) ---")
+var dir = TempFile.mkdtemp("_work", "demo_")
+System.print("Created directory: %(dir)")
+System.print("Is directory: %(Path.new(dir).isDir())")
+Path.new(dir).rmdir()
+
+System.print("\n--- NamedTemporaryFile ---")
+var tmp = NamedTemporaryFile.new(".txt", "demo_")
+System.print("Temp file: %(tmp.name)")
+tmp.write("Hello from tempfile module!")
+System.print("Content: %(tmp.read())")
+System.print("Auto-delete: %(tmp.delete)")
+tmp.close()
+System.print("Deleted after close: %(!(Path.new(tmp.name).exists()))")
+
+System.print("\n--- NamedTemporaryFile.use (context manager) ---")
+NamedTemporaryFile.new(".log").use {|f|
+    f.write("Log entry: operation completed")
+    System.print("Inside use block: %(f.read())")
+}
+System.print("Automatically cleaned up after use block")
+
+System.print("\n--- TemporaryDirectory ---")
+var tmpDir = TemporaryDirectory.new("_session", "demo_")
+System.print("Temp dir: %(tmpDir.name)")
+System.print("Is directory: %(tmpDir.path.isDir())")
+tmpDir.cleanup()
+System.print("Deleted after cleanup: %(!(Path.new(tmpDir.name).exists()))")
+
+System.print("\n--- TemporaryDirectory.use (context manager) ---")
+TemporaryDirectory.new().use {|d|
+    System.print("Working in: %(d.name)")
+    Path.new(d.name + "/data.txt").writeText("temporary data")
+    System.print("Created file inside temp dir")
+}
+System.print("Automatically cleaned up with all contents")
+
+System.print("\n=== Done ===")