Import march-2020-03-10 from private repo (scrubbed 2026-05-27)

Targets Rec Room 2020.03.10 client (also serves 2020.03.06).

Re-import after adding:
- DorkNet.ClientMod/dorknet-clientmod.json.template — config schema
  the launcher's manifest-driven patcher renders into UserData/.
- tools/build-patcher-zip.ps1 — produces dorknet-clientpatch-{key}.zip
  for v1-march-* Release uploads.
- .github/workflows/release.yml — on tag push publishes both
  dorknet-server-march_2020_03_10-win-x64.zip and
  dorknet-clientpatch-march_2020_03_10.zip as Release assets.

Same scrub rules as december; tools/build-patcher-zip.ps1 added to
the maintainer-side allow-list so it survives.

DorkNet.Server/Migrations/20260508152627_Phase3RoomDataBlobs.cs

@@ -0,0 +1,63 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DorkNet.Server.Migrations
+{
+    /// <inheritdoc />
+    public partial class Phase3RoomDataBlobs : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "CurrentDataBlobName",
+                table: "Rooms",
+                type: "TEXT",
+                maxLength: 128,
+                nullable: false,
+                defaultValue: "");
+
+            migrationBuilder.CreateTable(
+                name: "RoomDataBlobs",
+                columns: table => new
+                {
+                    Id = table.Column<long>(type: "INTEGER", nullable: false)
+                        .Annotation("Sqlite:Autoincrement", true),
+                    RoomId = table.Column<long>(type: "INTEGER", nullable: false),
+                    BlobName = table.Column<string>(type: "TEXT", maxLength: 128, nullable: false),
+                    UploadedByPlayerId = table.Column<long>(type: "INTEGER", nullable: false),
+                    UploadedAt = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    Bytes = table.Column<byte[]>(type: "BLOB", nullable: false),
+                    ReferencedFilenamesCsv = table.Column<string>(type: "TEXT", maxLength: 2048, nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_RoomDataBlobs", x => x.Id);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_RoomDataBlobs_BlobName",
+                table: "RoomDataBlobs",
+                column: "BlobName",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_RoomDataBlobs_RoomId",
+                table: "RoomDataBlobs",
+                column: "RoomId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "RoomDataBlobs");
+
+            migrationBuilder.DropColumn(
+                name: "CurrentDataBlobName",
+                table: "Rooms");
+        }
+    }
+}