shaders: -Dprebuilt-shaders, so a gui build needs no Vulkan SDK

glslc is the one build input that wants a tool a stock machine does not have,
and it is also the input that changes least often: eight GLSL files that have
outlived several rewrites of everything around them. Asking every machine that
wants to run the SDL shell for shaderc is the wrong trade.

The SPIR-V is now COMMITTED, under shaders/prebuilt/, and -Dprebuilt-shaders
embeds that copy instead of shelling out. The default stays the honest one --
compile the shaders that are actually in the tree -- because the flag trades a
dependency for a freshness problem: with it on, the .glsl sources are not build
inputs at all, so editing one changes nothing.

`zig build shaders` is the other half, and it is deliberately independent of
-Dplatform: it recompiles every shader and writes the result back into the
tracked directory, so whoever changes a shader refreshes the cache on a machine
that has the compiler and commits the diff. `jj diff shaders/prebuilt` after it
is the freshness check -- empty means the cache was already current.

The shader list is also spelled once now (gui_shaders): the eight embeds, the
eight glslc runs and the refresh step all read it, so adding a shader is a name
there plus the @embedFile in gui.zig, not three edits in two places.

Verified: -Dplatform=gui -Dprebuilt-shaders builds with glslc absent from PATH,
and image-harness passes on that binary -- real SDL GPU pipelines built from the
committed SPIR-V, 512 source pixels read back. The default gui build still runs
the eight glslc steps; tty runs none. The committed bytes are identical to a
fresh glslc run, and `zig build shaders` is idempotent.

1 files changed, 20 insertions, 20 deletions

diff --git a/test/snapshots/windowops.golden b/test/snapshots/windowops.golden
index 4101fa86..2ec3e46f 100644
--- a/test/snapshots/windowops.golden
+++ b/test/snapshots/windowops.golden
@@ -279,16 +279,16 @@
 |
 == snap debug-on grid=100x30 cursor=44,4
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/windowops/cwd New Del  /tmp/pardes-snap/windowops/c╭────────────────────────────╮
-|  ls                                      ls                          │pardes  resizes=1           │
-|  w.txt                                   w.txt                       │terms 4  cols 2             │
-|                                                                      │active #2  58x28            │
-|                                                                      │scroll 0/28                 │
-|                                                                      │pinch  1.0000               │
-|                                                                      │tscroll  0.0000             │
-|                                                                      ╰────────────────────────────╯
-|
-|
+|  /tmp/pardes-snap/windowops/cwd New Del  /tmp/pardes-snap/win╭────────────────────────────────────╮
+|  ls                                      ls                  │pardes  resizes=1                   │
+|  w.txt                                   w.txt               │theme  helix                        │
+|                                                              │font   default                      │
+|                                                              │terms 4  cols 2                     │
+|                                                              │active #2  58x28                    │
+|                                                              │scroll 0/28                         │
+|                                                              │pinch  1.0000                       │
+|                                                              │tscroll  0.0000                     │
+|                                                              ╰────────────────────────────────────╯
 |
 |  /tmp/pardes-snap/windowops/cwd New Del
 |  ls
@@ -310,16 +310,16 @@
 |
 == style debug-on
 |0: 0-56 #949494,#121212, 57-99 d,#121212,
-|1: 0-1 #ffffff,#262626, 2-39 #949494,#121212, 40-41 #ffffff,#626262, 42-69 #949494,#121212, 70-99 d,d,
-|2: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-87 #949494,d, 88-98 d,#121212, 99-99 d,d,
-|3: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-85 #949494,d, 86-98 d,#121212, 99-99 d,d,
-|4: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-86 #949494,d, 87-98 d,#121212, 99-99 d,d,
-|5: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-81 #949494,d, 82-98 d,#121212, 99-99 d,d,
-|6: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-83 #949494,d, 84-98 d,#121212, 99-99 d,d,
-|7: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-70 d,d, 71-85 #949494,d, 86-98 d,#121212, 99-99 d,d,
-|8: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-69 #bdbdbd,#080808, 70-99 d,d,
-|9: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-99 #bdbdbd,#080808,
-|10: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-99 #bdbdbd,#080808,
+|1: 0-1 #ffffff,#262626, 2-39 #949494,#121212, 40-41 #ffffff,#626262, 42-61 #949494,#121212, 62-99 d,d,
+|2: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-79 #949494,d, 80-98 d,#121212, 99-99 d,d,
+|3: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-74 #949494,d, 75-98 d,#121212, 99-99 d,d,
+|4: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-76 #949494,d, 77-98 d,#121212, 99-99 d,d,
+|5: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-77 #949494,d, 78-98 d,#121212, 99-99 d,d,
+|6: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-78 #949494,d, 79-98 d,#121212, 99-99 d,d,
+|7: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-73 #949494,d, 74-98 d,#121212, 99-99 d,d,
+|8: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-75 #949494,d, 76-98 d,#121212, 99-99 d,d,
+|9: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-62 d,d, 63-77 #949494,d, 78-98 d,#121212, 99-99 d,d,
+|10: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-61 #bdbdbd,#080808, 62-99 d,d,
 |11: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-99 #bdbdbd,#080808,
 |12: 0-1 #ffffff,#262626, 2-39 #949494,#121212, 40-40 d,#444444, 41-41 d,#080808, 42-99 #bdbdbd,#080808,
 |13: 0-0 d,#444444, 1-1 d,#080808, 2-39 #bdbdbd,#080808, 40-40 d,#444444, 41-41 d,#080808, 42-99 #bdbdbd,#080808,