Add ca65 as a standalone assembler under the Assembly language, reusing
the existing cc65 toolchain installations (2.17, 2.18, 2.19, trunk).
ca65 generates a listing file with full macro expansion (`-x -x`) so
users can debug macro output — the primary use case from the feature
request.
**What's included:**
- `Ca65Compiler` class — runs ca65, captures the listing output
- `AsmParserCa65` — parses the ca65 listing format (address, hex bytes,
source)
- Config for all 4 existing cc65 versions as ca65 assemblers
- Include paths set to each version's `asminc` directory
**How it works:**
Since ca65 produces object files in cc65's custom format (not ELF), we
can't objdump them. Instead, we use ca65's `-l` (listing) flag with `-x
-x` (full macro expansion) and `--list-bytes 0` (unlimited hex bytes per
line). The listing shows addresses, generated bytes, and expanded source
— exactly what users need for macro debugging.
Closes#7118
Co-authored-by: mattgodbolt-molty <mattgodbolt-molty@users.noreply.github.com>
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