make test no longer runs the frontend's production build (refs #118)

yarn build moves out of the stage that runs the frontend's unit tests,
now named frontend-test, into a frontend-build stage of its own. It
starts from frontend-test for its yarn packages and source, installs
the git that vite.config.js reads the commit with, and copies from the
lint and test phases as builder does, so it cannot run unless they
passed. The runtime stage copies dist/ from it. The Go compile, most of
make test's time, is unchanged and waits on the ruling asked for in
sneak/prompts#113; no build cache is added.

Model: opus-5-5

TODO.md

@@ -21,6 +21,14 @@ Run `make frontend-viewport-test` in CI as its own step; it is not part of
 
 # Completed Steps
 
+- 2026-10-14: `make test` no longer runs the frontend's production build, which
+  the tests do not need ([#118](https://git.eeqj.de/sneak/netwatch/issues/118)).
+  `yarn build` moved out of the stage that runs the frontend's unit tests, now
+  named `frontend-test`, into a new `frontend-build` stage, which starts from it
+  and, like the `builder` stage, waits on the lint and test phases, so the image
+  still cannot be built unless they pass. The runtime stage copies `dist/` from
+  it, and the `git` that `vite.config.js` reads the commit with is installed
+  there. No build cache was added
 - 2026-10-14: opening the debug log no longer raises the measured latencies
   ([#131](https://git.eeqj.de/sneak/netwatch/issues/131)). With the panel open,
   each line written drew the panel again with every line before it, up to 1000,
@@ -503,3 +511,9 @@ Run `make frontend-viewport-test` in CI as its own step; it is not part of
 - A configurable host list (an environment variable or a config file)
 - Export of the latency history (CSV or JSON)
 - A notification when the health status changes to DEGRADED
+- `make test` within the 20-second target
+  ([#118](https://git.eeqj.de/sneak/netwatch/issues/118)): every run compiles
+  the Go standard library and every dependency with the race detector from
+  nothing. Whether test builds may keep Go's compiled packages between runs
+  waits on sneak's ruling in
+  [prompts#113](https://git.eeqj.de/sneak/prompts/issues/113)