Create interrupt vectors at $FFFA-$FFFF

Add a convenience action that reads the six interrupt vector bytes at \$FFFA–\$FFFF and creates labelled entry points / functions in the current program:

| Address | Vector | Label |
|---------|--------|-------|
| \$FFFA–\$FFFB | NMI | `NMI_VECTOR` |
| \$FFFC–\$FFFD | RESET | `RESET_VECTOR` |
| \$FFFE–\$FFFF | IRQ/BRK | `IRQ_VECTOR` |

Steps:
1. Read the 6 bytes from the live VICE memory (or the loaded program image).
2. Dereference each 16-bit pointer.
3. Create a label and disassemble at the target address.

This gives immediate entry points for game disassembly — NMI and IRQ handlers contain most of the timing-critical game logic.

Can be a Ghidra script alongside `RebaseToC64Load.java`, or a remote method callable from the debugger.