Host-neutral Emacs editor capability.

The returned map is data plus functions. A host-specific adapter may wrap it
in its own editor protocol; hive-emacs never imports or resolves that host.

IEditorPort reification over the addon's verb handlers.

The port is the hive-spi contract face of hive-emacs.tools.emacs: same
params maps in, same MCP response maps out. Registered as the :default
editor port when the addon initializes; consumers resolve it through
hive-spi.editor.registry, never through this ns.

Surfaces implemented: substrate, buffer, docs. IEditorDaemonPort is
deliberately absent — hive-emacs' daemon layer has no verb handlers yet, so
the adapter reports the surface as unsupported rather than reifying methods
that would throw.

The addon's editor capabilities, published as data into hive-spi.

Function-level companion to hive-emacs.editor.port: the port answers the
MCP tool surface, this answers host code that just wants to evaluate
elisp or read the focused buffer. Both are registered at IAddon mount and
retracted at shutdown; neither is reachable except through hive-spi, so a
host never names a hive-emacs namespace.

Capability keys are the host-facing vocabulary — they intentionally match
the function names the host used to call directly, so the inversion is a
change of ROUTE, not of meaning.