chore: pin Tailwind 4.3.1, which drops module.register() (closes #355)

@tailwindcss/node 4.2.1, loaded by the Tailwind CLI, calls Node's
deprecated module.register() as it starts, so every make build on a
current Node printed the DEP0205 warning. 4.3.1 is the first release that
calls module.registerHooks() instead wherever Node has it.

tailwindcss and @tailwindcss/cli are pinned at exactly 4.3.1, and
yarn.lock carries the new versions of the packages they pull in. The
compiled CSS computes to the same values: it drops the unused .start and
.end rules and writes calc(var(--spacing) * 1) as var(--spacing).

Model: opus-5-5

TODO.md

@@ -45,6 +45,16 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-05: `make build` no longer prints the Node `DEP0205`
+  `module.register()` deprecation warning
+  ([#355](https://git.eeqj.de/sneak/AutistMask/issues/355)). The call came from
+  `@tailwindcss/node`, which the Tailwind CLI loads; `tailwindcss` and
+  `@tailwindcss/cli` are now pinned at 4.3.1, the first release that uses
+  `module.registerHooks()` where Node has it. The compiled CSS computes to the
+  same values; it drops the unused `.start` and `.end` rules and writes
+  `calc(var(--spacing) * 1)` as `var(--spacing)` and `calc(var(--spacing) * 0)`
+  as `0`.
+
 - 2026-10-05: `make dev` watches
   ([#332](https://git.eeqj.de/sneak/AutistMask/issues/332)). It used to pass
   `--watch` to a `build.js` that read no arguments, so it built once and exited.