chore(gitignore): fully ignore internal/web/dist, build stub included

The !internal/web/dist/.gitkeep exception kept the dist build stub
permanently visible as untracked noise and let it slip into commits four
separate times (each reverted with a 'drop the accidentally committed
dist build stub' commit). Nothing under dist/ is ever meant to be
tracked — make dist-stub and CI recreate the stub on disk — so drop the
whole exception block and let the plain dist/ rule cover it.

.gitignore

@@ -19,9 +19,6 @@ backup/
 bin/
 x-ui/
 dist/
-!internal/web/dist/
-internal/web/dist/*
-!internal/web/dist/.gitkeep
 release/
 node_modules/