feat(help): distinct help for advanced-mode SQL forms; split list by mode (#36)

The six advanced SQL DML/query forms (SELECT, WITH, SQL_INSERT, SQL_UPDATE,
SQL_DELETE, EXPLAIN_SQL) carried help_id: None, so `help select`/`help with`
resolved to nothing and `help insert` showed only the simple form. Give each
its own distinct help_id (data.select, data.sql_insert, …) with a hand-curated
help.data.* page. Distinct strings keep the dedup invariant intact, and
note_help_topic needs no change — `help insert` now shows the simple block and
the sql_insert block (like `help create` already did), and the advanced-only
forms resolve.

note_help now groups the list by CommandCategory: app-lifecycle commands first
(unlabelled), then "Simple-mode commands:" and "Advanced-mode (SQL) commands:"
sections — replacing the old single "DSL data commands (in simple mode):"
header, which used the banned "DSL" term and mis-labelled the advanced SQL
forms it already contained.

Four new help_command tests (red→green). Recorded as ADR-0024 Amendment 1;
CHANGELOG updated.

src/app.rs

@@ -3047,34 +3047,52 @@ impl App {
     /// output panel.
     ///
     /// Assembled from the command REGISTRY (ADR-0024 §help_id):
-    /// the framing (`help.intro`, `help.dsl_section`,
-    /// `help.types_reference`) comes from the catalog, and each
-    /// command's body is the catalog entry named by its
-    /// `help_id`. A newly-registered command appears here
-    /// automatically — no edit to this function or a hand-kept
+    /// the framing (`help.intro`, `help.simple_section`,
+    /// `help.advanced_section`, `help.types_reference`) comes from
+    /// the catalog, and each command's body is the catalog entry
+    /// named by its `help_id`. A newly-registered command appears
+    /// here automatically — no edit to this function or a hand-kept
     /// list. Each catalog line becomes its own `OutputLine` so
     /// the scroll-position math (one logical line = one display
     /// row) stays accurate per the renderer's invariant.
+    ///
+    /// Issue #36: the commands group by mode. App-lifecycle commands
+    /// (`help_id` in the `app.*` namespace) work in either mode and
+    /// list first, unlabelled, under the intro. The rest split by
+    /// [`CommandCategory`] into a simple-mode group and an
+    /// advanced-mode (SQL) group — replacing the old single "DSL data
+    /// commands (in simple mode)" header, which both used the banned
+    /// "DSL" term and wrongly claimed simple mode for the advanced SQL
+    /// forms the section already contained.
     fn note_help(&mut self) {
-        use crate::dsl::grammar::REGISTRY;
+        use crate::dsl::grammar::{CommandCategory, REGISTRY};
 
         let mut lines: Vec<String> = Vec::new();
         lines.push(crate::t!("help.intro"));
-        // REGISTRY is ordered app-commands first; emit the
-        // "DSL data commands" sub-header at the first command
-        // whose help_id leaves the `app.` namespace.
-        let mut dsl_header_done = false;
-        for (command, _category) in REGISTRY {
+
+        let mut simple: Vec<String> = Vec::new();
+        let mut advanced: Vec<String> = Vec::new();
+        for (command, category) in REGISTRY {
             let Some(help_id) = command.help_id else {
                 continue;
             };
-            if !dsl_header_done && !help_id.starts_with("app.") {
-                lines.push(crate::t!("help.dsl_section"));
-                dsl_header_done = true;
+            let body = crate::friendly::translate(&format!("help.{help_id}"), &[]);
+            let block: Vec<String> = body.lines().map(str::to_string).collect();
+            if help_id.starts_with("app.") {
+                lines.extend(block);
+            } else if matches!(category, CommandCategory::Advanced) {
+                advanced.extend(block);
+            } else {
+                simple.extend(block);
             }
-            let key = format!("help.{help_id}");
-            let body = crate::friendly::translate(&key, &[]);
-            lines.extend(body.lines().map(str::to_string));
+        }
+        if !simple.is_empty() {
+            lines.push(crate::t!("help.simple_section"));
+            lines.extend(simple);
+        }
+        if !advanced.is_empty() {
+            lines.push(crate::t!("help.advanced_section"));
+            lines.extend(advanced);
         }
         lines.extend(
             crate::t!("help.types_reference")