fix(ci): track web/dist .keep so go:embed resolves on bare checkout

The blanket dist/ pattern in .gitignore excluded the
apps/backend/internal/web/dist directory itself, making the earlier
.keep negation unreachable — the file was never committed, and CI's
clean checkout left //go:embed all:dist with no matching files.

Re-include the directory (contents remain ignored) and commit .keep.
Verified: go build ./... succeeds with dist containing only .keep.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

.gitignore

@@ -20,6 +20,9 @@ data/*
 .DS_Store
 coverage/
 dist/
+# the blanket dist/ above excludes the embedded-UI dir itself, which would
+# make the .keep negation unreachable — re-include the dir, contents stay ignored
+!apps/backend/internal/web/dist/
 
 # local tooling artifacts
 .playwright-mcp/