Production pass: floats, GC, type checking, and tooling

Adds floats, bitwise ops, UTF-8 strings with methods, try/catch,
closures, generics validation, a compile-time type checker, a
mark-and-sweep GC, source-level debug info, constant folding, and
the repl/fmt/package-manager commands.

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

vm/types.v

@@ -1,6 +1,8 @@
 // types.v — core types and constants for the VuurRaaf VM.
 module vm
 
+import obj
+
 const stack_cap = 65536
 
 // Field is one `name: value` entry of a struct value.
@@ -15,18 +17,38 @@ mut:
 	fields []Field
 }
 
+// Handler records a try/catch handler pushed at runtime.
+struct Closure {
+	entry int // code IP of the function body
+}
+
+struct Handler {
+	ip int // catch_ip
+	bp int // frame base at try point
+	sp int // stack pointer right after the handler record
+}
+
 struct Vm {
 mut:
-	code    []u8
-	strings []string
-	arrays  [][]i64
-	structs []StructVal
-	stack   []i64
-	sp      int
-	bp      int
-	ip      int
-	trace   bool
-	halted  bool
+	code      []u8
+	strings   []string
+	arrays    [][]i64
+	structs   []StructVal
+	floats    []f64
+	closures  []Closure
+	stack     []i64
+	sp        int
+	bp        int
+	ip        int
+	trace     bool
+	halted    bool
+	prog_args []string
+	exit_code i64
+	did_exit  bool
+	handlers  []Handler
+	lines     []obj.LineInfo // debug info: code offset -> source line
+	const_strs int          // strings[0..const_strs] are bytecode constants, never collected
+	last_heap  int          // heap size at the last GC check (allocation trigger)
 }
 
 fn bool_i64(b bool) i64 {