orb v0.4.0-alpha

A 3D model of the room, lit by the live rig.

STAGE 3D: venue.toml describes the room and round-trips; the stage-3d
panel renders it and draws a volumetric beam cone per fixture from the
live DMX frame. Fixture profiles gained [beam]; rig entries gained
orientation and mount. A room can be read from a photograph via
POST /api/venue/ingest, which returns a proposal and never a write, and
refuses an image with no scale anchor rather than inventing one.

CONSOLE: `sequence` reports instead of creating, `list <thing>` covers
everything worth listing, completion knows both commands and the show's
own sequence and cue names, the bar grows to show an answer, and
`music search` + `play 0, 2, 4` reach every provider.

SHELL: the top bar and edge docks stay put while the canvas scrolls; an
`empty` layout on l+x; a shared chooser on Shift+A then p, caret already
in its filter; a layout saves to and loads from browser, project or
config.

MUSIC: a play with no deck lands on a free one and leaves a sequence and
an executor to bind. A cue can no longer wedge the desk -- the frame loop
used to hold the World write lock across provider network I/O.

Also ships everything that had accumulated as Unreleased since 0.3.2-rc0:
the projects root, virtual MIDI twins, edit mode and binding inspector,
AI control with an action journal, the console command layer, the unified
show timeline, show persistence and seamless song looping.

Alpha: stage 3D is new and the venue schema may still move.