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>

release_docs/en/getting_started.md

@@ -0,0 +1,61 @@
+# Getting started
+
+## What's in the tarball
+
+After extracting `sprinter-c-v1.0-<host>.tar.gz` you've got:
+
+* **`bin/sprinter-cc`** — the C → SprintEXE driver (a bash script).
+* **`third_party/sdcc/`** — vendored SDCC 4.5 used for the C → Z80 step.
+* **`libc/include/`** — headers your programs include.
+* **`lib/sprinter.lib`** — the Sprinter target libc (prebuilt; rebuilt by `make` if you modify libc sources).
+* **`runtime/`** — crt0 variants and runtime helpers (assembled per-build).
+* **`toolchain/mkexe/`** — host utility that packs SDCC's `.ihx` into a SprintEXE.
+* **`examples/`** — 27 ready-to-build programs.
+* **`docs/{en,ru}/`** — this documentation.
+
+## First build
+
+```sh
+cd sprinter-c-v1.0-<host>
+make all                    # rebuild lib + every example (~30 s)
+```
+
+If `make` complains about a missing SDCC binary, fetch it once:
+
+```sh
+make sdcc                   # downloads SDCC 4.5 if not vendored
+```
+
+## Build your own program
+
+```sh
+cat > hello.c <<EOF
+#include <stdio.h>
+int main(void) {
+    puts("Hello, Sprinter!");
+    return 0;
+}
+EOF
+
+bin/sprinter-cc -o hello.exe hello.c
+```
+
+`hello.exe` is now a valid SprintEXE you can run on Sprinter / MAME / any
+ESTEX DSS shell.
+
+## Running on hardware or in an emulator
+
+The release does **not** include the MAME emulator or the Sprinter ROM /
+DSS / HDD images — those are large and have their own licensing.  To test:
+
+* **MAME:** install MAME 0.283+ separately, obtain Sprinter Sp2000 images from
+  Peters Plus, mount a FAT12 floppy with your `.exe` files as `-flop1`.
+* **Real Sprinter:** copy `.exe` to a floppy or HDD partition that DSS can
+  see, then `RUN HELLO` from the shell.
+
+## Next steps
+
+* Read `sprinter_cc.md` for compiler flags.
+* Read `memory_modes.md` when you start needing more than 14 KB of code.
+* Browse `examples/` — every file is a working program with comments.
+* See `headers.md` for the public API surface.