docs: extract goget manpage to standalone troff source

justfile

@@ -11,6 +11,10 @@ run:
 
 # Build the binary
 build:
+  # Keep the embedded manpage in sync with man/goget.1. //go:embed
+  # cannot reference files outside the embedding package, so we copy
+  # the source-of-truth manpage into the package tree before compiling.
+  cp man/goget.1 cmd/goget/man-page-data/goget.1
   go vet ./...
   gofmt -l $(find cmd internal pkg -name '*.go') | grep . && exit 1 || true
   go build -ldflags "-s -w" -o bin/goget ./cmd/goget
@@ -22,3 +26,22 @@ test:
 # Remove build artifacts
 uninstall:
   rm -rf bin/ coverage.out
+
+# Validate the manpage with groff (zero warnings on success). Requires
+# `groff` to be installed — skipped silently otherwise.
+man:
+  @command -v groff >/dev/null || { echo "groff not installed, skipping"; exit 0; }
+  groff -man -ww -Kutf-8 -z man/goget.1
+
+# Install the manpage to ~/.local/share/man/man1/ (XDG rootless).
+# After install, `man goget` resolves it automatically. Re-run safely to
+# pick up edits.
+install-man: man
+  @mkdir -p "$HOME/.local/share/man/man1"
+  gzip -c -f man/goget.1 > "$HOME/.local/share/man/man1/goget.1.gz"
+  @echo "Installed: $HOME/.local/share/man/man1/goget.1.gz"
+
+# Remove the manpage installed by `just install-man`.
+uninstall-man:
+  rm -f "$HOME/.local/share/man/man1/goget.1.gz"
+  @echo "Removed: $HOME/.local/share/man/man1/goget.1.gz"