40250 classic: increment 50 (Phase 1 W1) — §1.5 client version, §1.10 text codec, §2.2 two-packet merge

§1.5 CG_CLIENT_VERSION: send_client_version() now branches on locale. EUROPE
(this project's locale) sends CGClientVersion2 (header 0xf1, 67B, timestamp
"1215955205"); non-EUROPE sends CGClientVersion (0xfd) + CMake-injected
MT_BUILD_TIMESTAMP in C __TIMESTAMP__ form. New ClassicSession::set_executable_name()
(default "metin2.bin"; TODO(W0): M2Client passes OS::get_executable_path().get_file()).
m_version_sent set only after send_fixed() succeeds. wire_classic.h gains
CGClientVersion2 + size-table entry.

§1.10 fixed-length text: new extension/src/net/text_codec.h — to_wire()/
from_wire_str() apply a hard byte cap without splitting a UTF-8 multibyte
sequence; godot::String overloads are __has_include-guarded so mtnet stays
godot-free. classic_session.cpp routes 8 fixed-length name/sign/comment fills
through to_wire(); parser reads GC_CHAR_ADDITIONAL_INFO name via from_wire_str().
New net_text_codec_test (ctest net.text_codec). Locale codepage (CP949/CP1252)
transcoding remains a follow-up; wire bytes are currently UTF-8 (ASCII round-trips).

§2.2 two-packet PC/NPC merge: ClassicParser GC_CHARACTER_ADD drops invisible
races (20025/20038/20039); PC/NPC only stash a bare Entity into m_pending_actor;
everything else spawns immediately with a name from root/npclist.txt (new
npc_names.h + set_npclist_path(); $MT_ASSETS/$M2_ASSETS fallback; TODO(W0):
M2Client passes the asset root). GC_CHAR_ADDITIONAL_INFO with no pending entry
records m_last_error + m_unhandled_headers and drops (never half-creates);
on a hit it merges the pending Entity with the additional-info's 9 fields into
one mut_spawn_full() then erases the pending entry. New pending_actor_count()
test hook; net_classic_session_test updated (version assertions -> 0xf1;
stash -> merge -> spawn, immediate monster spawn, invisible-race drop,
no-pending additional-info is a no-op). Depends on W2 §2.2 steps 4-5
(entity_store mut_char_info touch / mut_shop_sign cleanup) — the merge works
with current W2 code as-is.

Build + ctest 17/17 (16 + net.text_codec); netbridge_test, p10_test green.
Docs: CLIENT-GAP.md W1 row + increment-50 change-log entry; CLIENT-GAP-FIX.md
§1.5/§1.10/§2.2 status + facts and C.5 batch record.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014yvAPqPivoY7vmBbzgqK4W

extension/CMakeLists.txt

@@ -28,6 +28,10 @@ add_library(mtnet STATIC
 target_include_directories(mtnet PUBLIC src/net)
 target_link_libraries(mtnet PUBLIC mt3p::sodium mt3p::minilzo mt3p::cryptopp)
 target_compile_features(mtnet PUBLIC cxx_std_20)
+# §1.5: non-EUROPE CG_CLIENT_VERSION timestamp, in C __TIMESTAMP__ form
+# ("Www Mmm dd hh:mm:ss yyyy"); regenerated on each CMake configure.
+string(TIMESTAMP MT_BUILD_TS "%a %b %d %H:%M:%S %Y")
+target_compile_definitions(mtnet PRIVATE MT_BUILD_TIMESTAMP="${MT_BUILD_TS}")
 
 # --- mtpack: m2dev-fork asset pack reader/writer (libsodium + zstd) ---
 add_library(mtpack STATIC
@@ -109,6 +113,10 @@ if(BUILD_TESTING AND MT_HOST_BUILD)
 	target_link_libraries(net_classic_mark_test PRIVATE mtnet)
 	add_test(NAME net.classic_mark COMMAND $<TARGET_FILE:net_classic_mark_test>)
 
+	add_executable(net_text_codec_test tests/net_text_codec_test.cpp)
+	target_link_libraries(net_text_codec_test PRIVATE mtnet)
+	add_test(NAME net.text_codec COMMAND $<TARGET_FILE:net_text_codec_test>)
+
     add_executable(net_mark_test tests/net_mark_test.cpp)
     target_link_libraries(net_mark_test PRIVATE mtnet mt3p::minilzo)
     add_test(NAME net.guild_mark COMMAND $<TARGET_FILE:net_mark_test>)