feat(website): schema-sidebar cast + Ctrl-O/Esc cast keys

Add a `schema-sidebar` cast that reveals the ADR-0046 sidebar with
Ctrl-O (the only way to show it at 90 cols) and steps through the
Tables and Relationships panels. Teach the generator the CtrlO/Esc
control codes; quote control codes so `^[`/`^]` stay valid YAML.

website/casts-src/generate.mjs

@@ -43,6 +43,12 @@ const NAMED_KEYS = {
   // `quit` command typed into the input — so the recording ends on the last
   // content frame rather than a dangling, payoff-less `quit`.
   CtrlC: '^C',
+  // Ctrl-O cycles the ADR-0046 schema-sidebar navigation focus
+  // (Input → Tables → Relationships → Input); the only way to reveal the
+  // sidebar in a 90-column cast (it auto-hides at that width).
+  CtrlO: '^O',
+  // Esc leaves navigation mode directly (back to the input field).
+  Esc: '^[',
 };
 
 /** Build the autocast `keys:` list (one entry per line) for a cast's steps. */
@@ -56,7 +62,9 @@ function keysFor(steps) {
     if (step.key != null) {
       const code = NAMED_KEYS[step.key];
       if (!code) throw new Error(`unknown key: ${step.key}`);
-      keys.push(code);
+      // Quote the control code so YAML-special bytes (`^[` ESC, `^]`) stay
+      // valid scalars; `^M`/`^I`/`^C` are unaffected by the quoting.
+      keys.push(JSON.stringify(code));
       if (step.after != null) keys.push(`${step.after}ms`);
       continue;
     }