feat(web): complete portable Blender feature gaps

web/protocol/sequencer.ts

@@ -424,3 +424,16 @@ export function gateSequencerCodec(requestValue: unknown, resultValue: unknown):
     return blockedGate("N-021", capability, [capabilityIssue("SEQUENCER_CODEC_UNSUPPORTED", error instanceof Error ? error.message : "Codec probe is invalid")]);
   }
 }
+
+/** Main-backed authoring commands for strip effects, transitions and color balance. */
+export const sequencerCommands = Object.freeze({
+  setStripModifiers(sceneId: string, stripId: string, modifiers: Array<{ id: string; type: string; enabled?: boolean; properties?: Record<string, unknown> }>) {
+    return { type: "setSequencerStripModifiers", sceneId, stripId, modifiers } as const;
+  },
+  setTransitions(sceneId: string, timeline: SequencerTimelineIR) {
+    return { type: "setSequencerTransitions", sceneId, timeline } as const;
+  },
+  setColorBalance(sceneId: string, stripId: string, colorBalance: { lift: [number, number, number]; gamma: [number, number, number]; gain: [number, number, number]; exposure?: number; contrast?: number; saturation?: number }) {
+    return { type: "setSequencerColorBalance", sceneId, stripId, colorBalance } as const;
+  },
+} as const);