refactor(playground): adopt remote/execute with pull-able schema, seed, and unified views

[skydread1]

remote

• Add public execute fn for transport-agnostic pattern execution (no HTTP needed)
• execute-pull kept as thin wrapper delegating to execute for backward compatibility
• Re-export execute from sg.flybot.pullable.remote public API

pull-playground

• Sandbox delegates to remote/execute instead of hand-rolling pattern compilation
• Schema and seed are now pull-able data in the store ({:schema ?s}, {:seed {nil true}})
• Collapse sandbox-api/remote-api into single flat pull-api with make-executor as only mode-specific fn
• Unify all defalias components as .cljc — reader conditionals only inside for JS-specific parts
• Uniform [::alias-name props] syntax in app-view, no platform split
• Remove dead state keys (schema-loading?, sample-data, schema-view-mode)
• Add Replicant to :dev deps for CLJ test classpath