Add full compiler toolchain, libc, examples and reference docs

First substantive commit: the entire Sprinter C compiler tree on top of
the bare README+gitignore initial commit.

What's in here:
  bin/sprinter-cc        — driver script invoking SDCC + linker + mkexe
  libc/                  — Sprinter-specific libc layer over ESTEX/BIOS
                           (conio, gfx, io, mem, stdio + headers)
  runtime/               — crt0 variants (default/small/banked/minimal)
                           + heap + bank trampolines
  toolchain/             — mkexe (SprintEXE packer, C + tests)
  examples/              — 30 demo programs (gfx, file I/O, env, time, …)
  lib/Makefile           — builds the libc archive (sprinter.lib)
  docs/                  — converted Sprinter manuals + asm reference samples
  third_party/           — solid-c reference compiler dump + sdcc setup script
  release_docs/          — packaging / release notes

gitignore overhaul:
  • Drop dangerous blanket patterns: *.asm (would hide docs/samples/*.asm)
    and *.exe (case-insensitive match was hiding third_party/solid-c/*.EXE
    on macOS APFS).  Replaced with examples/*/*.{asm,exe,…} and lib/*.lib.
  • Restore tracking of toolchain/mkexe/tests/{one,big}.bin — those are
    INPUT fixtures, not build outputs.
  • Collapse the duplicated SDCC/C/Sdcc sections into one section per
    concern (build outputs / vendored / OS-junk).
  • Add .sprinter-cc-*/, build/ (catches lib/build/ too), .claude/.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -1,64 +1,73 @@
-# ---> C
-# Prerequisites
-*.d
+# ===========================================================================
+# Build outputs
+# ===========================================================================
 
-# Object files
+# `build/` directories anywhere in the tree
+# (top-level build/, lib/build/, toolchain/*/build/, ...)
+build/
+
+# sprinter-cc per-example intermediate directory
+.sprinter-cc-*/
+
+# Per-example final/intermediate outputs landing alongside the source
+examples/*/*.exe
+examples/*/*.asm
+examples/*/*.lst
+examples/*/*.lk
+examples/*/*.ihx
+examples/*/*.noi
+examples/*/*.sym
+examples/*/*.map
+examples/*/*.rel
+examples/*/*.cdb
+examples/*/*.mem
+examples/*/*.rst
+
+# libc archive (built from libc/, see lib/Makefile)
+lib/*.lib
+
+# Host-built mkexe binary + test outputs (input fixtures *.bin/*.ihx kept)
+toolchain/mkexe/mkexe
+toolchain/mkexe/tests/*.exe
+toolchain/mkexe/tests/*.actual
+
+# Host-C build artifacts (mkexe and similar tools compiled with native cc)
 *.o
-*.ko
 *.obj
-*.elf
-
-# Linker output
-*.ilk
-*.map
-*.exp
-
-# Precompiled Headers
-*.gch
-*.pch
-
-# Libraries
-*.lib
-*.a
-*.la
-*.lo
-
-# Shared objects (inc. Windows DLLs)
-*.dll
-*.so
-*.so.*
-*.dylib
-
-# Executables
-*.exe
-*.out
-*.app
-*.i*86
-*.x86_64
-*.hex
-
-# Debug files
 *.dSYM/
-*.su
-*.idb
-*.pdb
 
-# Kernel Module Compile Results
-*.mod*
-*.cmd
-.tmp_versions/
-modules.order
-Module.symvers
-Mkfile.old
-dkms.conf
+# ===========================================================================
+# Vendored / downloaded
+# ===========================================================================
 
-# ---> Sdcc
-# SDCC stuff
-*.lnk
-*.lst
-*.map
-*.mem
-*.rel
-*.rst
-*.sym
+# SDCC: extracted source tree + download tarballs
+# (only third_party/setup-sdcc.sh tracked)
+third_party/sdcc/
+third_party/sdcc-*/
+third_party/*.tar.bz2
+third_party/*.tar.gz
 
+# MAME emulator install — ~1 GB binary + ROMs + CHDs
+mame/
+
+# ===========================================================================
+# OS / editor / AI assistant
+# ===========================================================================
+
+# macOS
+.DS_Store
+._*
+
+# Editor swap / backup
+*~
+*.swp
+*.bak
+*.orig
+*.rej
+
+# IDEs
+.vscode/
+.idea/
+
+# Claude Code local settings (per-machine, not for the repo)
+.claude/