feat(pipeline): standalone Blender renders on the same queue

Blender work is not a shot submission: no Export, no version, no
validation, QC or delivery. It is "Ctrl+F12, but on the farm", so it is
modelled as what it is — a queue entry and nothing more.

That turned out to need very little. Claim, progress, fail and
complete-render already tolerated a job with no Export behind them, so a
Blender job reuses the whole lifecycle; RenderJob gains projectId, label
and submittedBy so a job with no shot code still has something to show.

Capability gating is new and was already missing: the claim now filters
job types by the machine's reported tools. Without it a workstation
without Blender would claim Blender work and fail it repeatedly, burning
the attempts while a machine that could have rendered it sat idle. The
worker asks for Blender jobs unconditionally and the server refuses them
— trusting the worker to self-select would have left the same hole.

The runner treats a clean exit with no saved frames as a failure:
Blender exits 0 when a frame range is empty or an output path is
unwritable, and a job that silently rendered nothing is the worst
outcome available.

Standalone jobs auto-requeue on a transient failure like any other work;
delivery builds are deliberately excluded, since a half-written package
wants a human first.

Adds the Blender add-on (BlenderPanel/) and its docs. The add-on refuses
to submit an unsaved file — the farm opens the .blend from disk, so
unsaved changes would render the previous state without warning. Its
payload is pinned by a contract test, since add-on and server only ever
meet over JSON.

Worker 1.5.0. Adds migration 20260815000000_blender_render_jobs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

RenderWorker/VFXReviewWorker/Program.cs

@@ -41,6 +41,7 @@ builder.Services.AddSingleton<AerenderRunner>();
 builder.Services.AddSingleton<PreviewStage>();
 builder.Services.AddSingleton<ValidationStage>();
 builder.Services.AddSingleton<DeliveryStage>();
+builder.Services.AddSingleton<BlenderRunner>();
 builder.Services.AddSingleton<JobExecutor>();
 builder.Services.AddHostedService<WorkerService>();