docs: close the code fences that swallowed three pages

`docs/basics/routing.md`, `models.md` and `actions.md` each opened a code block
that never closed, so from that point everything rendered as code - headings,
prose, the lot. Roughly half of each page.

The cause is the same in all three: the OPENING fence went missing, leaving the
snippet bare under the frontmatter with a stray closer further down. In
`routing.md` it is clear where it went - the fence was swallowed into the
frontmatter, whose `description` field was two lines of TypeScript:

    description: "// Points to app/Controllers/ComingSoonController.ts, index
    method\nroute.get('/coming-soon', 'Controllers/ComingSoonController@index')"

That page now describes itself, and all three open their snippet properly.

Nothing caught this. `docs:links:check` reads links and the count checks read
counts; an unclosed fence is neither, which is why it sat there.

`docs-code-fences-close.test.ts` pairs the fences in every doc, and separately
looks for the shape that produced these: a line ending in `{`, `(` or `;`
immediately after the frontmatter is code that lost its fence, not a sentence.
Verified by removing the opener from `routing.md` again - the test names the
file.

Author: chrisbbreuer

docs/basics/actions.md

@@ -2,6 +2,7 @@
 title: Server Actions
 description: Learn how to create and use Actions in Stacks applications
 ---
+```typescript
   // Get specific keys only
   const credentials = request.only<{ email: string; password: string }>([
     'email',

docs/basics/models.md

@@ -3,6 +3,7 @@ title: Data Models
 description: Learn how to define and use ORM models in Stacks applications
 ---
 
+```typescript
 attributes: {
   name: {
     factory: faker => faker.person.fullName(),

docs/basics/routing.md

@@ -1,7 +1,8 @@
 ---
 title: Application Routing
-description: "// Points to app/Controllers/ComingSoonController.ts, index method\nroute.get('/coming-soon', 'Controllers/ComingSoonController@index')"
+description: Learn how routes map to Actions and Controllers in Stacks applications
 ---
+```typescript
 // Points to app/Controllers/ComingSoonController.ts, index method
 route.get('/coming-soon', 'Controllers/ComingSoonController@index')
 

storage/framework/core/buddy/tests/docs-code-fences-close.test.ts

@@ -0,0 +1,70 @@
+/**
+ * Every fenced code block in the docs is closed.
+ *
+ * Three pages under `docs/basics/` opened a block that never closed, so from
+ * that point the rest of the page rendered as code - headings, prose and all.
+ * The cause is the same in each: the opening fence went missing and the code
+ * sat bare under the frontmatter, with a stray closer further down. In
+ * `routing.md` the fence had been swallowed into the frontmatter itself, whose
+ * `description` was two lines of TypeScript.
+ *
+ * Nothing caught it. `docs:links:check` reads links, and the count checks read
+ * counts; an unclosed fence is neither.
+ */
+import { describe, expect, it } from 'bun:test'
+import { readdirSync, readFileSync, statSync } from 'node:fs'
+import { join } from 'node:path'
+
+const root = new URL('../../../../../', import.meta.url).pathname
+
+function markdownFiles(dir: string, found: string[] = []): string[] {
+  for (const entry of readdirSync(dir)) {
+    if (entry.startsWith('.'))
+      continue
+
+    const full = join(dir, entry)
+    if (statSync(full).isDirectory())
+      markdownFiles(full, found)
+    else if (entry.endsWith('.md'))
+      found.push(full)
+  }
+
+  return found
+}
+
+describe('documentation code fences', () => {
+  it('are all closed', () => {
+    const unclosed = markdownFiles(join(root, 'docs')).filter((file) => {
+      let open = false
+      for (const line of readFileSync(file, 'utf-8').split('\n')) {
+        // Only a fence at the start of a line delimits a block; an indented
+        // one inside a block is content.
+        if (line.startsWith('```'))
+          open = !open
+      }
+      return open
+    })
+
+    expect(unclosed.map(file => file.replace(root, '')).sort()).toEqual([])
+  })
+
+  it('never leave code bare under the frontmatter', () => {
+    // How all three broke: the opener vanished and the snippet became prose.
+    const bare = markdownFiles(join(root, 'docs')).filter((file) => {
+      const lines = readFileSync(file, 'utf-8').split('\n')
+      if (lines[0]?.trim() !== '---')
+        return false
+
+      const close = lines.findIndex((line, index) => index > 0 && line.trim() === '---')
+      if (close < 0)
+        return false
+
+      const first = lines.slice(close + 1).find(line => line.trim())
+      // A line ending in `{`, `(` or `;` right after the frontmatter is code
+      // that lost its fence, not a sentence.
+      return !!first && /[{(;]$/.test(first.trim()) && !first.startsWith('```')
+    })
+
+    expect(bare.map(file => file.replace(root, '')).sort()).toEqual([])
+  })
+})