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>

third_party/solid-c/INCLUDE/MOUSE.H

@@ -0,0 +1,112 @@
+/*
+ *	MOUSE.H
+ *
+ *	Defines structures, macros, and functions.
+ *	(c) 2004, SOLID C  Sprinter-2000
+ */
+
+
+#ifndef	_C_TYPES_
+#include <types.h>
+#endif
+
+
+#define LEFT_BUTTON	1
+#define RIGHT_BUTTON	2
+
+
+/* getStatMouse() */
+typedef	struct {
+	char button;		/* buttons: 0/1 bits - left/right */
+	char x;			/* colon */
+	char y;			/* line */
+} MSSTAT;
+
+
+/* getGStatMouse() */
+typedef	struct {
+	char button;		/* buttons: 0/1 bits - left/right */
+	int x;			/* X pos */
+	int y;			/* Y pos */
+} MSGSTAT;
+
+
+/* getCursMouse() */
+typedef	struct {
+	char width;		/* width curs */
+	char high;		/* high curs */
+	char xpoint;		/* X active point */
+	char ypoint;		/* Y active point */
+	char *buff;		/* addr cursor buffer */
+} MSCURS;
+
+
+/* setTxtMouse() */
+typedef	struct {
+	char xattr;		/* XOR attribut mask */
+	char aattr;		/* AND attribut mask */
+	char xsym;		/* XOR simbol mask */
+	char asym;		/* AND simbol mask */
+} MSTXT;
+
+
+/* getSensMouse(), setSensMouse() */
+typedef	struct {
+	char xsens;		/* horiz. sensitive */
+	char ysens;		/* vert. sensitive */
+} MSSENS;
+
+
+
+//	0 - ­¥â ®è¨¡®ª
+//	1 - ­¥¨§¢¥áâ­ ï äã­ªæ¨ï
+//	3 - ªãàá®à 㦥 ­  íªà ­¥
+//	4 - ªãàá®à ®âáãâáâ¢ã¥â ­  íªà ­¥
+//	5 - ¨§®¡à ¦¥­¨¥ ªãàá®à  ᫨誮¬ ¢¥«¨ª®
+
+/* Mouse Error Codes */
+#define MSEZERO		0		/* No error		*/
+#define MSUNKNW		1		/* Unknown function	*/
+#define MSEXIST		3		/* Exists cursor	*/
+#define MSNOCUR		4		/* No cursor		*/
+#define MSTOOBIG	5		/* Too big image	*/
+
+
+/* prototypes */
+
+char ms_init();
+char ms_show();
+char ms_hide();
+MSSTAT  *ms_stat();
+MSGSTAT *msgstat();
+char ms_spos();
+char mssgpos();
+char ms_ybnd();
+char ms_xbnd();
+char ms_scur();
+char ms_tcur();
+MSCURS *ms_gcur();
+MSSENS *ms_gsen();
+char ms_ssen();
+char ms_hard();
+char ms_vmod();
+char ms_ref();
+
+
+#define initMouse	ms_init
+#define showMouse	ms_show
+#define hideMouse	ms_hide
+#define getStatMouse	ms_stat
+#define getGStatMouse	msgstat
+#define setPosMouse	ms_spos
+#define setGPosMouse	mssgpos
+#define yLimMouse	ms_ybnd
+#define xLimMouse	ms_xbnd
+#define setTxtMouse	ms_tcur
+#define getCursMouse	ms_gcur
+#define setCursMouse	ms_scur
+#define getSensMouse	ms_gsen
+#define setSensMouse	ms_ssen
+#define hardMouse	ms_hard
+#define vmodeMouse	ms_vmod
+#define refreshMouse	ms_ref