Split the machine from its front end, and add Voyager

The Segan Voyager is the same SplitBit with a screen and a speaker instead of a terminal,
and this is the rung that makes there be two of them at all. Everything that is actually
the machine - the CPU, the controller, the devices, the run loop, the reporting - moves to
machine.c, and each front end brings one file of its own. emulator.c is now sixty lines of
argument handling and a three line loop.

The machine runs in SLICES rather than to completion, because that is the cut a window
needs: run a slice, present a frame, run another. A terminal runs slices until the machine
stops. Both loops are three lines, which is why the cut is there rather than anywhere else.

At this stage Voyager's window is empty. There is no video device yet and inventing a
temporary way to draw would mean building something to throw away.

PLAIN MAKE STILL WORKS WITH NO GRAPHICS LIBRARY. Raylib is probed by compiling and linking
against it rather than by looking for a file, because a header with no library behind it
passes a file check and then fails at link time. Where it is missing, make says so once and
builds everything else - the machine, the assembler, the disk tool, the linter and the whole
suite. A project about a small understandable CPU should not need OpenGL to run its tests.
That nearly broke here: make strict globs Source/Emulator/*.c, so it would have tried to
compile voyager.c and failed on precisely the machines the split exists to support, and this
machine has Raylib so nothing would have caught it.

Tests/voyager.sh runs the WHOLE MANIFEST through Voyager and holds it to the recorded
results SplitBit is held to. Not that the two look alike: that one satisfies every recording
the other does, byte for byte, exit status included. It reuses run.sh, which now takes the
machine from SPLITBIT_EMULATOR, rather than keeping a second copy of the runner that would
drift. Voyager not being built is not a failure - it says so and passes.

Verified both ways. Made Voyager print one extra line, and 114 of 165 failed: exactly the
tests that run the emulator, with the 51 assemble-only and xfail cases correctly untouched.
Removed the binary, and the script skipped. Built with HAVE_RAYLIB=no, and everything else
still built and checked clean.

--headless is taken out of the arguments in voyager.c rather than in the shared parser,
which should not learn about a window only one binary has. It exists so the suite can run
this binary at all: a front end that could only be exercised by a person looking at it would
be a front end nothing checks.

loadFile takes a const char * now, which it always should have.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

README.md

@@ -20,7 +20,7 @@ wrote Asm.sbx: program 7533, data 4099, labels 555
 
 | Directory | What it holds |
 | --- | --- |
-| [`Source/Emulator`](Source/Emulator) | The machine: CPU, memory controller, devices, console, disk |
+| [`Source/Emulator`](Source/Emulator) | The machine: CPU, memory controller, devices, console, disk - and the two front ends that present it |
 | [`Source/Assembler`](Source/Assembler) | The assembler that runs on a host |
 | [`Source/DiskTool`](Source/DiskTool) | SplitDisk, which reads and writes SplitBit's filesystem |
 | [`Source/Linter`](Source/Linter) | SplitLint, which points out needlessly long assembly forms |
@@ -31,6 +31,22 @@ wrote Asm.sbx: program 7533, data 4099, labels 555
 | [`Programs/testPrograms`](Programs/testPrograms) | What the test suite drives |
 | [`Tests`](Tests) | The suite: the manifest, the recorded output, and the scripts that check it |
 
+## Two Front Ends:
+
+`make` builds **SplitBit**, which is the machine with a terminal attached, and where Raylib
+is installed it also builds **Voyager**, which is the same machine with a screen and a
+speaker. Everything that is actually the machine - every instruction, every device, every
+cycle - is shared between them, and each brings one file of its own: a terminal or a window.
+
+Voyager is deliberately not required. The machine, the assembler, the disk tool, the linter
+and the whole test suite build and run on a host with no graphics library at all, because a
+project about a small understandable CPU should not need OpenGL to run its tests. Where
+Raylib is missing, `make` says so once and builds everything else.
+
+The suite holds the two to being the same machine rather than taking it on trust: it runs
+the entire manifest through Voyager as well, with `--headless`, and requires it to satisfy
+every recorded result byte for byte.
+
 ## The Machine:
 
 - **Harvard architecture.** Two 64K memories, one for instructions and one for data. An instruction can only read the second, which is why strings live there and why the memory controller exists.
@@ -512,7 +528,7 @@ $(BUILD)/%.bin: %.asm
 make test
 ```
 
-Builds the four tools, checks they build clean under strict ISO C, and runs seven scripts.
+Builds the four tools, checks they build clean under strict ISO C, and runs nine scripts.
 `Tests/run.sh` assembles and runs every program in `Programs/` and compares the results
 against recorded output; six more ask the questions a recorded file cannot answer. Between
 them they check the two assemblers against each other byte for byte, the two SBFS