Enhance label printing and add section boundaries to binary

[jackwthake]

• c02-objdump: label markers — jump target labels (L0:, L1:, ...) now
  print at the correct positions in the disassembly. The reset vector is read
  to translate between ROM buffer offsets and absolute addresses.
• c02-objdump: full opcode size table — the label pre-scan uses a 256-entry
  instruction size table covering the entire 65C02 instruction set, replacing
  the previous partial list that would lose sync on unrecognized opcodes.
• c02-objdump: section-aware output — the code generator now writes a
  code/data boundary address at $FFF8 in the ROM. The disassembler reads
  this to stop before the data section, with a NOP-fill heuristic fallback
  for older binaries.
• c02-objdump: new CLI flags —
  -a / --all shows disassembly followed by a .data hex dump with ASCII.
  -d / --data dumps just the .data section.
  -s / --sections prints the section layout (.text, .data, vectors
  with addresses).