Add structured Pointer system (CREATEPTR, GETPTR, SETPTR)

[DigitalCodeCrafter]

Closes #3154
This PR introduces a new, fully backward-compatible pointer system for low-level kOS bytecode.
It enables indirect access to stack entries, variables, and nested data structures.

This feature is intended for assembly authors and compiler backends.
It has no effect on normal Kerboscript unless future changes to the compiler are made.

Summary

New PointerValue structure

• Stores a list of segments describing how to resolve a value.
• Segment rules:
  • First Segment (root):
    • ScalarIntValue: absolute stack index
    • StringValue beginning with $: variable name
  • Remaining segments:
    • Keys / indices for nested structures (lists, lexicons, etc.)
• Not enumerable or indexable; only used via dedicated opcodes.

New opcodes

Opcode	Stack Input	Output	Description
CREATEPTR n	segN .. seg1	ptr	Builds a pointer from n stack segments
GETPTR	ptr	value	Resolves a pointer and pushes the referenced value
SETPTR	value ptr	--	Writes value to the referenced location
ALLOCATE n	--	Null ... Null	Pushes n nulls onto the stack (reserves stack space)
FREE n	...	--	Pops n value from the stack (releases stack space)
STACKPTR	--	sp	Pushes the current stack pointer (stack length).
INSTPTR	--	ip	Pushes the current instruction pointer.

These replace the previously proposed PEEK/POKE/STORNAME approach with a more flexible and extensible system.

Compatibility

• No changes to existing opcodes.
• No behavioral impact on existing scripts.
• PointerValue inaccessible to normal Kerboscript
• Only programs explicitly using the new opcodes are affected.