Apply macro expansion to teardown commands and fix @def continuation parsing

Teardown commands were missing the expandMacro call that setup and
parsed commands already received. Also relax the continuation-line
guard to catch bare `$` (not just `$ `) so lines like `$VAR` are
not silently consumed as continuation text.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/cli/index.ts

@@ -150,7 +150,7 @@ program
         commands: [
           ...setupCommands.map(expandMacro),
           ...parsed.commands.map(expandMacro),
-          ...teardownCommands,
+          ...teardownCommands.map(expandMacro),
         ],
       }
 

src/parse.ts

@@ -82,7 +82,7 @@ function parseDefDirective(
 
   while (body.endsWith("\\") && i + extra + 1 < rawLines.length) {
     const next = rawLines[i + extra + 1]!
-    if (next.startsWith("$ ") || next.startsWith("@")) {
+    if (next.startsWith("$") || next.startsWith("@")) {
       throw new Error(`${path}:${i + extra + 2}: @def continuation consumed a command or directive line`)
     }
     body = body.slice(0, -1).trimEnd() + "\n" + next.trim()