modules: split services and the ircd link into external crates

nickserv, chanserv and the InspIRCd protocol move out of the binary into their
own workspace crates (fedserv-nickserv, fedserv-chanserv, fedserv-inspircd),
each depending only on fedserv-api. human_time and the branded account emails
move into the SDK crate so a module needs nothing from core; the engine keeps
its own inherent methods and builds emails via fedserv-api too. The bin now
constructs each module from its crate instead of an in-tree #[path] include.
Proves the SDK is self-sufficient: a third-party module is the same shape.

chanserv/src/entrymsg.rs

@@ -0,0 +1,36 @@
+use fedserv_api::Store;
+use fedserv_api::{Sender, ServiceCtx};
+
+// ENTRYMSG <#channel> [CLEAR | <text>]: message noticed to users as they join.
+// With no argument, show the current message.
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, db: &mut dyn Store) {
+    let Some(&chan) = args.get(1) else {
+        ctx.notice(me, from.uid, "Syntax: ENTRYMSG <#channel> [CLEAR | <text>]");
+        return;
+    };
+    match args.get(2) {
+        None => match db.channel(chan) {
+            None => ctx.notice(me, from.uid, format!("\x02{chan}\x02 isn't registered.")),
+            Some(info) if info.entrymsg.is_empty() => ctx.notice(me, from.uid, format!("\x02{chan}\x02 has no entry message.")),
+            Some(info) => ctx.notice(me, from.uid, format!("Entry message for \x02{chan}\x02: {}", info.entrymsg)),
+        },
+        Some(&kw) if kw.eq_ignore_ascii_case("CLEAR") => {
+            if !super::require_op(me, from, chan, ctx, db) {
+                return;
+            }
+            match db.set_entrymsg(chan, "") {
+                Ok(()) => ctx.notice(me, from.uid, format!("Entry message for \x02{chan}\x02 cleared.")),
+                Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+            }
+        }
+        Some(_) => {
+            if !super::require_op(me, from, chan, ctx, db) {
+                return;
+            }
+            match db.set_entrymsg(chan, &args[2..].join(" ")) {
+                Ok(()) => ctx.notice(me, from.uid, format!("Entry message for \x02{chan}\x02 updated.")),
+                Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+            }
+        }
+    }
+}