build: fix Docker/Cloud Run source deploy ignores

.dockerignore excluded plugin/, which is now a compiled package
(plugin/embed.go embeds SKILL.md). Add .gcloudignore so source uploads
skip node_modules; anchor /bdrive so cmd/bdrive isn't excluded.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UdqEkKvj4Dc2d718mcV6EY

.dockerignore

@@ -6,5 +6,4 @@ website
 *.md
 .goreleaser.yaml
 .claude
-plugin
 /private

.gcloudignore

@@ -0,0 +1,6 @@
+.git
+node_modules/
+/bdrive
+/dist/
+/web/docs/dist/
+/private