2.3 Startup vs reload asymmetry (FramesRegistry)

FramesRegistry validates strictly on construction (fail-fast at startup) and
leniently on hot-reload (skip invalid frames with a warning, keep valid ones
serving). Exposes TryGetByName/TryGetByMac over the current valid set.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/FrameProcessor/Domain/Frame.cs

@@ -0,0 +1,14 @@
+namespace FrameProcessor.Domain;
+
+/// <summary>
+/// A configured frame after validation and parsing. All raw strings from
+/// <c>frames.json</c> have been converted to their typed values; consumers can use
+/// the contents directly without re-validating.
+/// </summary>
+public sealed record Frame(
+    FrameName Name,
+    MacAddress Mac,
+    Resolution Resolution,
+    Orientation Orientation,
+    DitherAlgorithm Dithering,
+    IReadOnlyList<PaletteEntry> Palette);