Label C64 hardware registers

Add a convenience action (Ghidra script or remote method) that applies standard C64 hardware register labels to the current program/trace.

Ranges to cover:

- \$D000–\$D3FF — VIC-II (video)
- \$D400–\$D7FF — SID (audio)
- \$D800–\$DBFF — Color RAM
- \$DC00–\$DCFF — CIA 1 (keyboard/joystick)
- \$DD00–\$DDFF — CIA 2 (serial/NMI)
- \$DE00–\$DFFF — I/O expansion

Without these, every `STA $D011` or `LDA $DC01` is opaque during game disassembly.

Can be implemented as a Ghidra headless script (like `RebaseToC64Load.java`) that applies labels and plate comments, runnable on import or on demand from the debugger.