feat(announcement): add server-side announcement functions and handlers

Implement server-side announcement system with the following features:
- LimitChars() utility function to safely truncate strings with UTF-8 support
- bladw_amenu concommand to open announcement menu for players
- /bannonce and !bannonce chat commands as aliases for the menu
- Resolve() function to merge announcement presets with custom entries
- Broadcast() function to send announcements to all clients with proper length limits
- Net message receiver for admin announcement submissions
- Resource file declaration for sound asset download

lua/bladw_announcement/server/sv_function.lua

@@ -0,0 +1,79 @@
+BladW = BladW or {}
+BladW.Announcement = BladW.Announcement or {}
+
+-- pour que les clients téléchargent le son
+resource.AddFile("sound/announce.mp3")
+
+-- coupe une chaîne à maxChars caractères (propre avec les accents)
+local function LimitChars(str, maxChars)
+    str = tostring(str or "")
+    local n = utf8.len(str)
+    if not n or n <= maxChars then return str end
+    local endByte = utf8.offset(str, maxChars + 1)
+    return endByte and string.sub(str, 1, endByte - 1) or str
+end
+
+-- ouvre le menu pour le joueur
+concommand.Add("bladw_amenu", function(ply, cmd)
+    if not IsValid(ply) then return end
+
+    net.Start("bladWOpenAnnouncementMenu")
+    net.Send(ply)
+end)
+
+-- /bannonce (ou !bannonce) dans le chat = ouvre le menu
+hook.Add("PlayerSay", "BladW:AnnouncementChatCmd", function(ply, text)
+    local cmd = string.lower(string.Trim(text))
+    if cmd ~= "/bannonce" and cmd ~= "!bannonce" then return end
+    if not IsValid(ply) then return end
+
+    net.Start("bladWOpenAnnouncementMenu")
+    net.Send(ply)
+
+    return "" -- pour pas laisser la commande dans le chat
+end)
+
+-- reconstruit l'annonce finale : le preset sert de base, title/text passent devant
+function BladW.Announcement.Resolve(entry)
+    local presets = BladW.Announcement.Presets or {}
+    local base    = (entry.preset and presets[entry.preset]) or {}
+
+    return {
+        title    = (entry.title and entry.title ~= "" and entry.title) or base.title or "Annonce",
+        text     = (entry.text  and entry.text  ~= "" and entry.text ) or base.text  or "",
+        style    = entry.style or base.style or "",
+        duration = tonumber(entry.duration) or tonumber(base.duration) or 0,
+    }
+end
+
+-- envoie l'annonce à tout le monde. false si y'a rien à envoyer
+function BladW.Announcement.Broadcast(entry)
+    local a = BladW.Announcement.Resolve(entry)
+    if a.text == "" then return false end
+
+    local maxLen = tonumber((BladW.Announcement.Conf or {}).announcement_max_length) or 120
+
+    net.Start("bladWShowAnnouncement")
+        net.WriteString(LimitChars(a.title, 64))
+        net.WriteString(LimitChars(a.text, maxLen))
+        net.WriteString(a.style or "")
+        net.WriteUInt(math.Clamp(a.duration, 0, 65535), 16)
+    net.Broadcast()
+
+    return true
+end
+
+-- un admin veut poster une annonce -> je la diffuse
+net.Receive("bladWSendAnnouncement", function(len, ply)
+    if not IsValid(ply) or not ply:IsAdmin() then return end
+
+    local preset = net.ReadString()
+    local title  = net.ReadString()
+    local text   = net.ReadString()
+
+    BladW.Announcement.Broadcast({
+        preset = preset ~= "" and preset or nil,
+        title  = title,
+        text   = text,
+    })
+end)