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/access.rs

@@ -0,0 +1,70 @@
+use fedserv_api::Store;
+use fedserv_api::{Sender, ServiceCtx};
+
+// ACCESS <#channel> LIST | ADD <account> <op|voice> | DEL <account>
+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: ACCESS <#channel> LIST | ADD <account> <op|voice> | DEL <account>");
+        return;
+    };
+    match args.get(2).map(|s| s.to_ascii_uppercase()).as_deref() {
+        None | Some("LIST") => match db.channel(chan) {
+            None => ctx.notice(me, from.uid, format!("\x02{chan}\x02 isn't registered.")),
+            Some(info) => {
+                ctx.notice(me, from.uid, format!("Access list for \x02{}\x02:", info.name));
+                ctx.notice(me, from.uid, format!("  \x02{}\x02 (founder)", info.founder));
+                for a in &info.access {
+                    ctx.notice(me, from.uid, format!("  \x02{}\x02 ({})", a.account, a.level));
+                }
+            }
+        },
+        Some("ADD") => {
+            let (Some(&account), Some(&level)) = (args.get(3), args.get(4)) else {
+                ctx.notice(me, from.uid, "Syntax: ACCESS <#channel> ADD <account> <op|voice>");
+                return;
+            };
+            let level = level.to_ascii_lowercase();
+            if level != "op" && level != "voice" {
+                ctx.notice(me, from.uid, "Level must be \x02op\x02 or \x02voice\x02.");
+                return;
+            }
+            if !is_founder(me, from, chan, ctx, db) {
+                return;
+            }
+            match db.access_add(chan, account, &level) {
+                Ok(()) => ctx.notice(me, from.uid, format!("Added \x02{account}\x02 to \x02{chan}\x02 as \x02{level}\x02.")),
+                Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+            }
+        }
+        Some("DEL") => {
+            let Some(&account) = args.get(3) else {
+                ctx.notice(me, from.uid, "Syntax: ACCESS <#channel> DEL <account>");
+                return;
+            };
+            if !is_founder(me, from, chan, ctx, db) {
+                return;
+            }
+            match db.access_del(chan, account) {
+                Ok(true) => ctx.notice(me, from.uid, format!("Removed \x02{account}\x02 from \x02{chan}\x02.")),
+                Ok(false) => ctx.notice(me, from.uid, format!("\x02{account}\x02 has no access to \x02{chan}\x02.")),
+                Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+            }
+        }
+        _ => ctx.notice(me, from.uid, "Syntax: ACCESS <#channel> LIST | ADD <account> <op|voice> | DEL <account>"),
+    }
+}
+
+// True if `from` is the channel's founder; otherwise notices why and returns false.
+fn is_founder(me: &str, from: &Sender, chan: &str, ctx: &mut ServiceCtx, db: &dyn Store) -> bool {
+    match db.channel(chan) {
+        None => {
+            ctx.notice(me, from.uid, format!("\x02{chan}\x02 isn't registered."));
+            false
+        }
+        Some(info) if from.account != Some(info.founder.as_str()) => {
+            ctx.notice(me, from.uid, format!("Only \x02{chan}\x02's founder can change access."));
+            false
+        }
+        Some(_) => true,
+    }
+}