Variable pmtilesProtocolManifestConst Experimental

pmtilesProtocolManifest: HonuaPluginManifest<"protocol"> = ...

Manifest for the first-party PMTiles protocol plugin. It certifies through the same #392 kit as every out-of-tree plugin and requests no grants: discovery never touches the network (the reader opens lazily on the handle's own describe() call), so there is no origin or credential scope to request up front.