feat(ugc): answer the client's UGC manifest requests without 3D services

With UGCUSE3DSERVICES=7:0 (the client's default) the client asks its world for
a blueprint file's MD5 and size (REQUEST_UGC_MANIFEST_INFO, world 27) and then
downloads BrickModels/UserMade/<id % 1000>/<id>.<ext>.sd0. Layouts checked in
the 1.10.64 client: the request is a u64 blueprint id and a u8 resource type;
the answer (UGC_MANIFEST_RESPONSE, client 60) repeats them and adds a u8 valid,
the u32 size and the 16 byte MD5 of the inflated file, 37 bytes after the 0x53
exactly or the client drops it.

- dNet: WorldPackets::RequestUgcManifestInfo, ClientPackets::UgcManifestResponse
  (eUgcResourceType), with byte tests against the client's layouts.
- Database: ugc_file_checksums (per model or module combination and file) and
  ugc_modular_build.combination_id (migrations 89 / 72), GetUgcFileChecksum
  looks a blueprint up as a model, else as a build through its combination.
- UGC server: every download is also written as .sd0 (Sd0::Compress); workers
  hand the checksums back and the main thread stores them; old items get their
  sd0 icon and checksum, and builds their combination id, once at start-up, a
  few per tick; serves <dir>/BrickModels/UserMade/<bucket>/<id>.<ext>.sd0 under
  client_path, /<folder>/UserBrickModels and the root (.hkx 404).
- World: UgcManifest answers on the main thread with one indexed query per
  request; files not made yet are answered when they are (looked at again
  every 5 seconds), and a model in its quiet period is made right away. No
  worker threads, HTTP or file reads in the world.

Off by default (ugc_manifest=0): checked in game, the client then downloads
from http://127.0.0.1:80/lwoclient/UserBrickModels/ whatever its boot.cfg says
and logs the player out when it can't connect, so icons need the UGC server on
port 80 of each player's machine. docs/UgcServer.md has the details.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDatabase/GameDatabase/MySQL/MySQLDatabase.h

@@ -429,6 +429,10 @@ public:
 	void DeleteUgcIconSettings(const std::string_view target) override;
 	void SetUgcModelProcessed(const LWOOBJID id, const eProcessState state, const uint32_t attempts, const std::string_view error, const bool bakeAo) override;
 	void SetUgcModelStats(const LWOOBJID id, const uint32_t bricks, const uint32_t triangles) override;
+	void SetUgcFileChecksum(const eFileOwner owner, const LWOOBJID storageId, const std::string_view file, const std::string_view md5, const uint32_t size) override;
+	std::optional<IUgc::FileChecksum> GetUgcFileChecksum(const LWOOBJID blueprintId, const std::string_view file) override;
+	void SetModularBuildCombination(const LWOOBJID id, const LWOOBJID combinationId) override;
+	std::vector<IUgcModularBuild::PendingBuild> GetModularBuildsWithoutCombination(const uint32_t limit) override;
 	std::optional<IUgc::ProcessInfo> GetUgcProcessInfo(const LWOOBJID id) override;
 	uint64_t ResetUgcModelProcessing(const std::optional<LWOOBJID> id, const bool failedOnly) override;
 	std::vector<IUgc::ProcessInfo> GetUgcProcessList(const std::optional<eProcessState> state, const std::string_view search, const uint32_t offset, const uint32_t limit) override;

dDatabase/GameDatabase/MySQL/Tables/Ugc.cpp

@@ -181,3 +181,16 @@ void MySQLDatabase::ExpediteUgcModels(const LWOOBJID characterId) {
 void MySQLDatabase::SetUgcModelStats(const LWOOBJID id, const uint32_t bricks, const uint32_t triangles) {
 	ExecuteUpdate("UPDATE ugc SET brick_count = ?, triangle_count = ? WHERE id = ?;", bricks, triangles, id);
 }
+
+void MySQLDatabase::SetUgcFileChecksum(const eFileOwner owner, const LWOOBJID storageId, const std::string_view file, const std::string_view md5, const uint32_t size) {
+	ExecuteInsert("INSERT INTO ugc_file_checksums (kind, storage_id, file, md5, size) VALUES (?, ?, ?, ?, ?) "
+		"ON DUPLICATE KEY UPDATE md5 = VALUES(md5), size = VALUES(size);", static_cast<int32_t>(owner), storageId, file, md5, size);
+}
+
+std::optional<IUgc::FileChecksum> MySQLDatabase::GetUgcFileChecksum(const LWOOBJID blueprintId, const std::string_view file) {
+	auto result = ExecuteSelect("SELECT md5, size FROM ugc_file_checksums WHERE kind = 0 AND storage_id = ? AND file = ? "
+		"UNION ALL SELECT f.md5, f.size FROM ugc_modular_build b JOIN ugc_file_checksums f ON f.kind = 1 AND f.storage_id = b.combination_id AND f.file = ? "
+		"WHERE b.ugc_id = ? AND b.combination_id != 0 LIMIT 1;", blueprintId, file, file, blueprintId);
+	if (!result->next()) return std::nullopt;
+	return IUgc::FileChecksum{ std::string(result->getString("md5").c_str()), static_cast<uint32_t>(result->getUInt("size")) };
+}

dDatabase/GameDatabase/MySQL/Tables/UgcModularBuild.cpp

@@ -106,3 +106,16 @@ void MySQLDatabase::SetUgcIconSettings(const std::string_view target, const std:
 void MySQLDatabase::DeleteUgcIconSettings(const std::string_view target) {
 	ExecuteDelete("DELETE FROM ugc_icon_settings WHERE target = ?;", target);
 }
+
+void MySQLDatabase::SetModularBuildCombination(const LWOOBJID id, const LWOOBJID combinationId) {
+	ExecuteUpdate("UPDATE ugc_modular_build SET combination_id = ? WHERE ugc_id = ?;", combinationId, id);
+}
+
+std::vector<IUgcModularBuild::PendingBuild> MySQLDatabase::GetModularBuildsWithoutCombination(const uint32_t limit) {
+	auto result = ExecuteSelect("SELECT ugc_id, ldf_config, process_attempts FROM ugc_modular_build WHERE combination_id = 0 LIMIT ?;", limit);
+	std::vector<PendingBuild> builds;
+	while (result->next()) {
+		builds.push_back({ result->getInt64("ugc_id"), std::string(result->getString("ldf_config").c_str()), static_cast<uint32_t>(result->getInt("process_attempts")) });
+	}
+	return builds;
+}