v1.0.0

C02 v1.0.0: Complete Single-File Language

C02 has reached its v1.0 milestone. Per the goal set out in docs/roadmap.md:
someone can sit down and write a non-trivial 65C02 program without hitting an
"unimplemented" wall. Every must-have and should-have feature on the v1.0
checklist is now implemented and tested.

Highlights

• break and continue now work inside while and for loops.
• Local string literal initializers: u8 *p = "..."; works inside
  function bodies, not just at global scope.
• 16-bit multiply, divide, and modulo (__mul16, __div16, __sdiv16).
• __heap_start and __memory_top implicit globals for bump allocators
  and RAM top queries, injected automatically into every translation unit.
• Embedded ROM symbol table: compiled binaries now carry function names,
  so c02-objdump shows real labels instead of auto-generated ones.

Correctness fixes

• Variable shadowing is now a semantic error instead of a silent miscompile.
  Codegen identifies variables by name only, with no scope qualifier, so a
  shadowed inner declaration could alias the same storage as its outer
  namesake (this is what caused a break bug fixed this cycle). Shadowing an
  enclosing scope is now rejected at analysis time.
• Signed 8-bit division and modulo (i8) previously routed through the
  unsigned helper and produced wrong results for negative operands. Fixed
  with a new __sdiv8 wrapper.
• Binary operations with mixed width or mixed signedness (u8 + u16,
  i8 < u8) derived their result type from the left operand only, silently
  dropping high bytes or producing inconsistent comparisons depending on
  operand order. Both operands now normalize to a common type first.

Safety and robustness

• ROM writes are now bounds checked. A program that exceeds the 32 KB ROM
  fails with a clear diagnostic instead of silently corrupting the output.
• Zero page exhaustion now fails codegen cleanly instead of warning and
  continuing.

Testing

285 tests passing: golden tests, smoke tests, emulator tests, and valgrind
leak checks, all under make test. New coverage this cycle includes
emulator tests for break, continue (in both loop forms), 16-bit
multiply/divide, and mixed-width/mixed-sign binary operations.

What's not in v1.0

A short, deliberate list of nice-to-haves the roadmap explicitly allows v1.0
to ship without: short-circuit &&/|| evaluation outside a boolean
context, and the bitwise/shift compound assignment operators (&=, |=,
^=, <<=, >>=). Arrays and multi-file linking are scoped for later
milestones (v1.2+).

What's next

v1.1 is planned to bring interrupt handlers and inline assembly. See
docs/roadmap.md for the full plan through v2.0.