fix(chat-filter): portable .dcf hashing, block list phrases

The filter stored and compared words by std::hash<std::string> in size_t,
which differs between standard libraries and platforms, so a .dcf made on
one system never matched on another and the block list never worked
there (issue 215).

- ChatFilterCore.h: 64-bit FNV-1a over the entry's bytes, ASCII lower
  case, fixed-width uint64_t everywhere stored or compared.
- .dcf version 3: little-endian magic, version, longest entry in words,
  uint64 count and sorted uint64 hashes. Version 2 files are refused:
  the allowed words cache is rebuilt from its .txt, an old
  blocklist.dcf is logged as unreadable.
- The servers build blocklist.dcf from a plain blocklist.txt next to
  them (one word or phrase per line) when it is newer.
- Blocked entries can be phrases: runs of consecutive words up to the
  longest entry, the whole run marked. Whitelist chat still checks one
  word at a time, as the client does.
- Dashboard: the chat filter API reads blocklist.dcf the same way
  (status, phrase length), accepts blocked phrases, refuses allowed
  ones, and explains phrase matches in its message test.

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

tests/dCommonTests/CMakeLists.txt

@@ -39,6 +39,7 @@ set(DCOMMONTEST_SOURCES
 	"FdbReaderTests.cpp"
 	"FdbSnapshotTests.cpp"
 	"WorldFileWatchTests.cpp"
+	"ChatFilterCoreTests.cpp"
 )
 
 add_subdirectory(dEnumsTests)
@@ -59,6 +60,8 @@ endif()
 target_link_libraries(dCommonTests ${COMMON_LIBRARIES} MD5 GTest::gtest_main)
 # SpareBackoff.h (header only)
 target_include_directories(dCommonTests PRIVATE "${PROJECT_SOURCE_DIR}/dMasterServer")
+# ChatFilterCore.h (header only)
+target_include_directories(dCommonTests PRIVATE "${PROJECT_SOURCE_DIR}/dChatFilter")
 
 # Copy test files to testing directory
 add_subdirectory(TestBitStreams)