docs: overhaul Pawn include documentation

[Nord1cWarr1or]

🖤

Purpose

The Pawn includes had drifted from the C++ they document: wrong return types and parameter names, misspelled constants (ITDB_* should be ITBD_* per basemonster.h), whole constant families missing. This PR is a full documentation pass over the include layer, plus a CS-filtered expansion of cssdk_const.inc and a Reunion constants split.

No module behavior is changed — the only C++ edits are doc comments in natives_*.cpp. Existing enum members are not shifted anywhere, so old compiled plugins are unaffected, with two intentional renames noted below.

Approach

1. Engine layer (reapi_engine.inc, reapi_engine_const.inc)

• added the missing Return type: for RH_GetEntityInit and RH_SV_CheckUserInfo
• fixed factual errors: get_ucmd (usercmd handle, not entity), get_key_value_buffer (returns cell count), rh_get_client_connect_time (@error instead of a soft 0), Is/ResetModifiedMessageData (MsgIndex → MsgMsgId, -1 argument rules), net_remote_address setter marked not implemented (mutate via set_netadr)
• new SND_EMIT2_USE_ORIGIN define; ~20 typo/copy-paste doc fixes (lenght, metchan, mvar params, message_const.inc reference, etc.)

2. cssdk_const.inc — rework and expansion

Renames (breaking for out-of-tree plugins that used the old spellings; in-tree usage checked — none):

• ITDB_* → ITBD_* (plus NERVE_GAS/DROWN_RECOVER/SLOW_BURN/SLOW_FREEZE underscores) — per C++ basemonster.h
• SHIELDREN_* → SHIELDGREN_* — per real game code (wpn_shared/)

Alias (non-breaking): DMG_EXPLOSION added next to DMG_GRENADE (the ReGameDLL name of the bit).

New constants — each verified against ReGameDLL/ReHLDS headers and checked for in-game consumers; the name-collision sweep vs amxmodx core and reapi includes is clean:

• item flags: ITEM_FLAG_EXHAUST_SECONDARYAMMO, ITEM_FLAG_CUSTOM
• player: PLAYER_PREVENT_DDUCK, IN_ACTIVE, ThrowDirection, PlayerIdShowHealth, PlayerIdField
• game rules: RewardAccount, PaybackForBadThing, SCENARIO_BLOCK_*, DefuserAllocation, CS_KILLS_FOR_DOMINATION
• weapons: WeaponInfiniteAmmoMode, AmmoType (numbering follows C++, differs from AMXX CsAmmoType), WeaponCostType, ItemCostType, AmmoCostType, ClipGiveDefault, ClipSizeType, WeightWeapon, MaxAmmoType, AutoBuyClassType, WEAPON_SUIT, WEAPON_ALLWEAPONS, WEAPON_ACTIVITY_VOLUME, KNIFE_BODYHIT/WALLHIT_VOLUME
• messages/HUD: BOMB_FLAG_*, STATUSICON_*, HUD_PRINT*, STATUS_NIGHTVISION_*, ITEM_STATUS_*, FFADE_*, SBAR_*, DHF_*/DHM_*
• hitboxes: NUM_HITGROUPS; time-based damage: ITBD_END
• misc: BLOOD_COLOR_DARKRED, GROUP_OP_AND/NAND, VIEW_FIELD_*, CHAN_BOT, MAX_AMMO_SLOTS, MAX_ITEMS, DEFAULT_FOV, NUM_BLENDING, ANIM_SWIM_1/2, ANIM_FIRST_DEATH_SEQUENCE, SF_GAMECOUNTSET_FIREONCE, SF_GAME_PZONE_ONLY_ALIVE, SF_PLAYEREQUIP_REMOVEWEAPONS, SF_GUNTARGET_START_ON, SF_SPARK_TOOGLE/IF_OFF ("TOOGLE" preserved from C++)

Deliberately not added: HL-only relics that CS never sets — EF_NIGHTVISION/SNIPERLASER/FIBERCAMERA and SATCHELCODE have zero consumers in either fork. Keeps the file CS-applicable. Comment fixes: PFLAG_DUCKING ("not"), DEAD_RESPAWNABLE, WeaponState weapon list, FEV_RELIABLE tail, light section header.

3. reapi_gamedll_const.inc

• added missing Return type: lines: RG_RoundEnd, RG_HandleMenu_ChooseTeam, RG_CBasePlayer_TakeHealth, RG_CBasePlayer_SetClientUserInfoName, RG_CBasePlayer_Observer_IsValidTarget (with ATYPE_CLASSPTR note), RG_CBasePlayer_HasRestrictItem
• KickBack: full weapon list + up_max param name fix; m_pVIP/m_pVIPQueue relabeled to class CBasePlayer *; m_iIgnoreGlobalChat typed IgnoreChatMsg

4. Reunion API split — constants moved to the new reapi_reunion_const.inc (client_auth_type, reu_authkey_kind, AuthIdType); documented REU_GetAuthKeyKind, REU_SetConnectTime, REU_GetSerializedId.

5. reapi.inc / reapi_rechecker.inc — hookchain native documentation corrected; RegisterQueryFile contract documented.

6. C++ doc sync — natives_common.cpp: get_key_value_buffer doc synced with the .inc, mixed-up amx_GetBodygroup/amx_SetBodygroup doc blocks swapped; natives_misc.cpp: "independant ... with via" typo.

Open Questions and Pre-Merge TODOs

• Every added constant has an in-game consumer; HL-only relics left out on purpose.
• No value/order shifts of existing enum members — additions are append-only, and the positional .inc ↔ member_list.h ↔ member_list.cpp mapping stays in sync.
• Name-collision word-boundary sweep vs amxmodx core and reapi includes — clean.
• CRLF line endings preserved.

Learning

Audit method: 235 engine-layer checks and 983 cssdk-constant checks against the ReHLDS/ReGameDLL sources, plus a global reverse sweep of ~95 constant families. PLAYER_PREVENT_DDUCK supersedes #392 (the same single constant, added here with the full PLAYER_* iuser3 context). The renames are the only breaking part — affected plugins need a two-line rename. Module bug fixes follow separately in #390; the VTC API 3.1 work is #396.

See also: #392, #390, #396