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>

docs/samples/sprinterKeybLib.asm

@@ -0,0 +1,140 @@
+; Библиотека работы с клавиатурой
+keybLibrary
+
+COM_A   EQU     19h
+DAT_A   EQU     18h
+
+;From z84c15 SIO instruction
+;COM_A Read
+;d0 - Rx Character available
+;d1 - Int panding (Ch.A only)
+;d2 - Tx buffer empty
+;d3 - DCD
+;d4 - Syan/Hunt
+;d5 - CTS
+;d6 - Tx Under.../ EOM
+;d7 - Break/Abort
+;Note: d3-d7 used with "External Status Interrupt" Modes
+
+; Установка портов режима
+; в соответствии с описанием
+; последовательного порта z84c15
+; use: a
+keybLibInit
+    ld a,#00
+    out (COM_A),a
+    ld a,#01
+    out (COM_A),a
+    ld a,#00
+    out (COM_A),a
+    ld a,#03
+    out (COM_A),a
+    ld a,#c1
+    out (COM_A),a
+    ld a,#04
+    out (COM_A),a
+    ld a,#05
+    out (COM_A),a
+    ld a,#05
+    out (COM_A),a
+    ld a,#62
+    out (COM_A),a
+    ret
+
+
+; Считывание с клавиатуры пр прерываниям
+; use: hl,de,af
+keybIntHandler
+    ld hl,keybBufferSize
+    ld de,(_keybBufferPosWrite)
+_keybIntHandlerLoop
+    in a,(COM_A)
+    bit 0,a         ; проверить наличие байта
+    ret z           ; вернуться, если нет байта
+    in a,(DAT_A)    ; считать байт
+    ld (de),a
+    inc e
+    ld (_keybBufferPosWrite),de
+    inc (hl)
+    jp _keybIntHandlerLoop
+
+
+; Очистка буфера
+; use: hl,af
+keybClearBuff
+    di
+    xor a
+    ld (keybBufferSize),a
+    ld hl,keybBuffer
+    ld (keybBufferPosRead),hl
+    ld (_keybBufferPosWrite),hl
+_keybClearBuffLoop
+    in a,(COM_A)
+    bit 0,a         ; проверить наличие байта
+    ret z           ; вернуться, если нет байта
+    in a,(DAT_A)    ; считать байт
+    jp _keybClearBuffLoop
+
+
+; Читаем и декодируем данные из буфера
+; use: hl,de,af
+; ret:
+;   a - code (0 if no data)
+;   carry=1 if release =0 if presseed
+keybGetKey
+    ld hl,keybBufferSize
+    ld de,(keybBufferPosRead)
+    ld a,(hl)
+    ld b,a
+    or a
+    ret z
+    ld a,(de): inc e
+    cp #f0
+    jr z,keybGetKeyF0; release
+    cp #e0
+    jr z,keybGetKeyE0; prefix E0
+    ld (keybBufferPosRead),de: dec (hl)
+keybGetKeyHasKeyPressed
+    and a
+keybGetKeyHasKey
+    ld h,#40
+    ld l,a
+    ld a,(hl)
+    ret
+keybGetKeyF0; release
+    dec (hl)
+    jr z,keybGetKeyNoData
+    ld a,(de): inc e
+    ld (keybBufferPosRead),de: dec (hl)
+    scf
+    jr keybGetKeyHasKey
+keybGetKeyE0; prefix E0
+    dec (hl)
+    jr z,keybGetKeyNoData
+    ld a,(de): inc e
+    cp #f0
+    jr z,keybGetKeyE0F0; prefix E0, release
+    ld (keybBufferPosRead),de: dec (hl)
+    add a,#80
+    jr keybGetKeyHasKeyPressed
+keybGetKeyE0F0; prefix E0,release
+    dec (hl)
+    jr z,keybGetKeyNoData2
+    ld a,(de): inc e
+    ld (keybBufferPosRead),de: dec (hl)
+    add a,#80
+    scf
+    jr keybGetKeyHasKey
+keybGetKeyNoData2
+    inc (hl)
+keybGetKeyNoData
+    inc (hl)
+    xor a
+    ret
+
+keybBufferSize db 0
+keybBufferPosRead dw keybBuffer
+_keybBufferPosWrite dw keybBuffer
+
+    align 256
+keybBuffer ds 256,0