Display seam for external DMD output (real / virtual / colorized)

[freezy]

Small, additive changes to the GLE display seam so an external package
(VisualPinball.Engine.DMD) can fan display frames out to real DMD hardware, an on-screen virtual DMD, and a colorization stage without touching the in-scene rendering path. Also includes two small correctness/perf fixes in the in-scene DMD.

No behavior changes for existing setups. Every addition is opt-in and ReceiveGamelogicFrames
defaults to the current behavior.

Game/Engine/IGamelogicEngine.cs - two optional capability interfaces + a documented contract:

• IRomNameProvider { string RomName } - lets a consumer resolve the active ROM (for colorization
  lookup) without reflection.
• IDisplayFrameFormatPreference { void RequestDisplayFrameFormat(string displayId, DisplayFrameFormat format) } - lets a consumer request a frame format per display (e.g. Dmd4 for colorization vs Dmd8).
• Documented the threading / buffer-ownership contract on OnDisplayUpdateFrame: it must be
  raised on the Unity main thread, and DisplayFrameData.Data is only valid for the duration of the
  call (a subscriber that hands it to a worker thread must copy it).

Gamelogic engines opt in by implementing the interfaces (PinMAME does so in its own repo); engines
that don't are unaffected.

Display/DisplayComponent.cs - adds bool ReceiveGamelogicFrames (default true). When an
external owner (e.g. the DMD bridge's in-scene destination) takes over a display, it flips this off
so the built-in DisplayPlayer stops writing that display's texture.

Game/DisplayPlayer.cs - honors ReceiveGamelogicFrames on frame-update, clear, and
display-requested events (the last one prevents a blank-frame flicker and a redundant Texture2D
reallocation when an externally-owned display is re-requested mid-game). Minor TryGetValue cleanups.

Display/DotMatrixDisplayComponent.cs

• RGB24 frames are now copied to the texture with a vertical row flip, matching the orientation of
  the gray (Dmd2/4/8) path (CopyData gained a destination offset so it can copy row-by-row).
• The gray palette lookup uses a single TryGetValue instead of ContainsKey + indexer (two
  dictionary lookups per pixel → one).
• Removed a stray FLIPX debug log.

[greptile-apps]

Greptile Summary

This PR adds an opt-in seam for external DMD frame handling. The main changes are:

• Added a ReceiveGamelogicFrames flag for display ownership.
• Skipped built-in display updates, clears, and resize requests when that flag is disabled.
• Added optional game-logic capability interfaces for ROM names and display frame format requests.
• Documented the display frame threading and buffer lifetime contract.
• Flipped RGB24 DMD texture copies to match the grayscale path.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
VisualPinball.Unity/VisualPinball.Unity/Display/DisplayComponent.cs	Adds the opt-in frame ownership flag with the existing behavior kept as the default.
VisualPinball.Unity/VisualPinball.Unity/Display/DotMatrixDisplayComponent.cs	Flips RGB24 frame rows during raw texture copy and simplifies grayscale palette lookup.
VisualPinball.Unity/VisualPinball.Unity/Game/DisplayPlayer.cs	Skips display configuration, clearing, and frame updates for externally owned displays.
VisualPinball.Unity/VisualPinball.Unity/Game/Engine/IGamelogicEngine.cs	Adds optional display-related capability interfaces and documents the frame event contract.

_{Reviews (1): Last reviewed commit: "dmd: Skip externally-owned displays on d..." | Re-trigger Greptile}