feat: add patch series, build scripts and release automation

scripts/export-patches.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Regenerate patches/ from the commits in build/upstream.
+#
+# Run this after changing anything in the patched checkout: every commit on top
+# of the upstream tag becomes one patch file, and patch files that no longer
+# have a commit behind them are deleted.
+
+. "$(dirname "${BASH_SOURCE[0]}")/common.sh"
+
+require_worktree
+
+if [ -n "$(git -C "$WORKTREE" status --porcelain)" ]; then
+	die "$WORKTREE has uncommitted changes. Commit them first: each commit becomes one patch."
+fi
+
+count="$(git -C "$WORKTREE" rev-list --count "$UPSTREAM_REF..HEAD")"
+[ "$count" -gt 0 ] || die "No commits on top of $UPSTREAM_REF to export."
+
+log "Exporting $count patches"
+rm -f "$PATCH_DIR"/*.patch
+git -C "$WORKTREE" format-patch \
+	--binary \
+	--zero-commit \
+	--no-signature \
+	--no-numbered \
+	--output-directory "$PATCH_DIR" \
+	"$UPSTREAM_REF..HEAD"
+
+log "patches/ now contains:"
+ls -1 "$PATCH_DIR"