fix(export): render Lightning frames with WebGL and allow software H.264

Lightning exports failed on Linux with "Cannot read properties of undefined
(reading '_resourceType')". The export renderer preferred WebGPU whenever
navigator.gpu existed, but the preview renderer always prefers WebGL, so
exports ran on a backend that never worked on this machine. PixiJS then read
a missing filter resource in BindGroupSystem._createBindGroup and threw.

Breeze was separately unreachable on Linux: its Annex B encoder probe only
tried prefer-hardware, while electron/gpuSwitches.ts disables
VaapiVideoDecoder and VaapiVideoEncoder on Linux, so the probe rejected the
software encoder that WebCodecs had already reported as supported.

- Default the export renderer to WebGL-first to match VideoPlayback.tsx;
  keep WebGPU available when explicitly requested.
- Probe Breeze with prefer-hardware and fall back to prefer-software, and
  configure the encoder with whichever config passed.

src/lib/exporter/modernFrameRenderer.ts

@@ -623,14 +623,13 @@ export class FrameRenderer {
 		};
 
 		const preferredRenderBackend = this.config.preferredRenderBackend;
+		// Default to WebGL to match the preview renderer (VideoPlayback.tsx) and
+		// the legacy export renderer, so exported frames render on the same
+		// backend users see while editing. WebGPU remains available when it is
+		// explicitly requested; unproven WebGPU support has failed mid-export
+		// inside PixiJS bind-group setup on some Linux drivers.
 		const backendOrder: ExportRenderBackend[] =
-			preferredRenderBackend === "webgl"
-				? ["webgl", "webgpu"]
-				: preferredRenderBackend === "webgpu"
-					? ["webgpu", "webgl"]
-					: typeof navigator !== "undefined" && "gpu" in navigator
-						? ["webgpu", "webgl"]
-						: ["webgl"];
+			preferredRenderBackend === "webgpu" ? ["webgpu", "webgl"] : ["webgl", "webgpu"];
 		const failures: PixiRendererAttempt[] = [];
 
 		for (const backend of backendOrder) {

src/lib/exporter/modernVideoExporter.ts

@@ -2780,21 +2780,38 @@ export class ModernVideoExporter {
 			return false;
 		}
 
-		const encoderConfig: VideoEncoderConfig = {
+		const buildEncoderConfig = (
+			hardwareAcceleration: VideoEncoderConfig["hardwareAcceleration"],
+		): VideoEncoderConfig => ({
 			codec: "avc1.640034",
 			width: this.config.width,
 			height: this.config.height,
 			bitrate: this.config.bitrate,
 			framerate: this.config.frameRate,
-			hardwareAcceleration: "prefer-hardware",
+			hardwareAcceleration,
 			avc: { format: "annexb" },
-		};
+		});
+
+		// Prefer hardware H.264, but fall back to software. Recordly disables
+		// VA-API on Linux (see electron/gpuSwitches.ts), so hardware encoding is
+		// frequently unavailable there even though software encoding works.
+		let encoderConfig = buildEncoderConfig("prefer-hardware");
 
 		try {
 			const support = await VideoEncoder.isConfigSupported(encoderConfig);
 			if (!support.supported) {
-				this.lastNativeExportError = `H.264 Annex B encoding is not supported at ${this.config.width}x${this.config.height}.`;
-				return false;
+				const softwareConfig = buildEncoderConfig("prefer-software");
+				const softwareSupport = await VideoEncoder.isConfigSupported(softwareConfig);
+
+				if (!softwareSupport.supported) {
+					this.lastNativeExportError = `H.264 Annex B encoding is not supported at ${this.config.width}x${this.config.height}.`;
+					return false;
+				}
+
+				encoderConfig = softwareConfig;
+				console.warn(
+					`[VideoExporter] ${NATIVE_EXPORT_ENGINE_NAME} hardware H.264 encoding is unavailable at ${this.config.width}x${this.config.height}; using software encoding instead.`,
+				);
 			}
 		} catch (error) {
 			this.lastNativeExportError = error instanceof Error ? error.message : String(error);

src/lib/exporter/videoExporter.ts

@@ -686,23 +686,39 @@ export class VideoExporter {
 			return false;
 		}
 
-		const encoderConfig: VideoEncoderConfig = {
+		const buildEncoderConfig = (
+			hardwareAcceleration: VideoEncoderConfig["hardwareAcceleration"],
+		): VideoEncoderConfig => ({
 			codec: "avc1.640034",
 			width: this.config.width,
 			height: this.config.height,
 			bitrate: this.config.bitrate,
 			framerate: this.config.frameRate,
-			hardwareAcceleration: "prefer-hardware",
+			hardwareAcceleration,
 			avc: { format: "annexb" },
-		};
+		});
+
+		// Hardware H.264 is unavailable on many Linux builds because VA-API is
+		// disabled (see electron/gpuSwitches.ts); software encoding still works.
+		let encoderConfig = buildEncoderConfig("prefer-hardware");
 
 		try {
 			const support = await VideoEncoder.isConfigSupported(encoderConfig);
 			if (!support.supported) {
+				const softwareConfig = buildEncoderConfig("prefer-software");
+				const softwareSupport = await VideoEncoder.isConfigSupported(softwareConfig);
+
+				if (!softwareSupport.supported) {
+					console.warn(
+						`[VideoExporter] Native H.264 Annex B encoding is unsupported at ${this.config.width}x${this.config.height}`,
+					);
+					return false;
+				}
+
+				encoderConfig = softwareConfig;
 				console.warn(
-					`[VideoExporter] Native H.264 Annex B encoding is unsupported at ${this.config.width}x${this.config.height}`,
+					`[VideoExporter] Native hardware H.264 encoding is unavailable at ${this.config.width}x${this.config.height}; using software encoding instead.`,
 				);
-				return false;
 			}
 		} catch (error) {
 			console.warn("[VideoExporter] Native encoder support check failed:", error);