remove q quit alias

`q` was introduced in round-5 as a peer Keyword variant alongside
`quit`. Per ADR-0023's "alias miss" critique, that was the wrong
shape — it surfaced `q` as a standalone command in completion
(only one of its kind), and required parallel parser + usage +
catalog + test entries. Drops the Keyword variant entirely; if
this ever needs to come back, it should arrive as an alias
annotation per ADR-0023, not as a peer keyword.

Tests still 769 passing.

src/dsl/keyword.rs

@@ -112,7 +112,6 @@ define_keywords! {
     // routing so these work in both simple and advanced modes
     // (per ADR-0003).
     Quit => "quit",
-    Q => "q",
     Help => "help",
     Rebuild => "rebuild",
     Save => "save",

src/dsl/parser.rs

@@ -469,8 +469,7 @@ fn command_parser<'a>()
     // BEFORE chumsky runs; the bare-keyword forms below
     // surface the `Path: None` / no-source variants for
     // empty-prompt completion + usage rendering.
-    let quit_cmd = choice((kw(Keyword::Quit), kw(Keyword::Q)))
-        .map(|()| Command::App(AppCommand::Quit));
+    let quit_cmd = kw(Keyword::Quit).map(|()| Command::App(AppCommand::Quit));
     let help_cmd = kw(Keyword::Help).map(|()| Command::App(AppCommand::Help));
     let rebuild_cmd =
         kw(Keyword::Rebuild).map(|()| Command::App(AppCommand::Rebuild));

src/dsl/usage.rs

@@ -99,10 +99,6 @@ pub const REGISTRY: &[UsageEntry] = &[
         entry: Keyword::Quit,
         catalog_key: "parse.usage.quit",
     },
-    UsageEntry {
-        entry: Keyword::Q,
-        catalog_key: "parse.usage.quit",
-    },
     UsageEntry {
         entry: Keyword::Help,
         catalog_key: "parse.usage.help",
@@ -220,7 +216,6 @@ mod tests {
             Keyword::Delete,
             Keyword::Replay,
             Keyword::Quit,
-            Keyword::Q,
             Keyword::Help,
             Keyword::Rebuild,
             Keyword::Save,
@@ -308,16 +303,15 @@ mod tests {
     fn entry_keywords_alphabetised_returns_unique_sorted_commands() {
         let keys = entry_keywords_alphabetised();
         let names: Vec<&str> = keys.iter().map(|k| k.as_str()).collect();
-        // Ten DSL entries plus the eleven app-lifecycle entries
-        // registered in REGISTRY (quit/q are two keywords with
-        // the same usage template; both surface here).
+        // Ten DSL entries plus the ten app-lifecycle entries
+        // registered in REGISTRY.
         assert_eq!(
             names,
             vec![
                 "add", "change", "create", "delete", "drop", "export",
                 "help", "import", "insert", "load", "messages", "mode",
-                "new", "q", "quit", "rebuild", "rename", "replay",
-                "save", "show", "update",
+                "new", "quit", "rebuild", "rename", "replay", "save",
+                "show", "update",
             ],
         );
     }