test: add markdown stress test for table rendering

Covers feature matrix tables, alignment torture (left/center/right),
nested structures (lists, blockquotes, code blocks), inline chaos,
fenced blocks, horizontal rules, single-column tables, tables inside
blockquotes, and math blocks.

Author: ImmanuelHaffner

test/stress.md

@@ -0,0 +1,109 @@
+Here's a stress test for your markdown renderer:
+
+---
+
+### Feature Matrix
+
+
+| Feature | Status | Docs |
+|---------|--------|------|
+| **Bold** & *Italic* | ✅ Done | [spec](https://spec.commonmark.org/0.31.2/#emphasis-and-strong-emphasis-with-asterisks-and-underscores-rule-1-through-17) |
+| ~~Strikethrough~~ | ⚠️ Partial | [GFM](https://github.github.com/gfm/#strikethrough-extension-with-tildes-and-double-tildes-for-del-elements) |
+| `inline code` | ✅ Done | [ref](https://spec.commonmark.org/0.31.2/#code-spans-backtick-strings-and-their-matching-rules-for-inline-code) |
+| Nested lists | 🔧 WIP | [deep](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#nested-lists-ordered-and-unordered-mixing-indentation-levels) |
+
+### Alignment Torture
+
+| Left | Center | Right | Mixed |
+|:-----|:------:|------:|-------|
+| `vim.api` | **strong** | 42 | [API](https://neovim.io/doc/user/api.html#nvim_buf_set_lines()-nvim_buf_get_lines()-and-other-buffer-manipulation-functions) |
+| `vim.lsp` | *emphasis* | 3.14 | [LSP](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_completion_resolve_and_other_request_types) |
+| `vim.treesitter` | ***both*** | 0xDEAD | [TS](https://tree-sitter.github.io/tree-sitter/using-parsers/queries/pattern-matching-with-predicates-and-anchors#the-match-predicate) |
+
+### Nested Structures
+
+1. **First level**
+   - Bullet with `code` and [a link](https://example.com)
+   - Another bullet
+     1. Ordered inside unordered
+     2. With a table inside:
+
+        | Key | Val |
+        |-----|-----|
+        | `a` | 1   |
+
+     3. Back to the list
+   - > A blockquote inside a list item
+     > spanning multiple lines
+2. **Second level** — with a long code block:
+
+   ````lua
+   local M = {}
+   -- nested code fences should survive
+   function M.setup(opts)
+     opts = vim.tbl_deep_extend("force", {
+       enabled = true,
+       style = { bold = true, italic = false },
+     }, opts or {})
+     return opts
+   end
+   return M
+   ````
+
+3. ***Third*** with a task list:
+   - [x] Completed task
+   - [ ] Pending task
+   - [ ] Another one
+
+### Inline Chaos
+
+This paragraph has **bold**, *italic*, ***bold-italic***, `inline code`, ~~deleted~~, and [a very descriptively titled link](https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.29.1.tgz#some-very-long-anchor-fragment-that-keeps-going-and-going-forever) all in one sentence.
+
+### Fenced Blocks Parade
+
+````python
+# Python
+def f(x: int) -> dict[str, list[int]]:
+    return {"result": [i**2 for i in range(x)]}
+````
+
+````bash
+# Shell with pipes
+cat /proc/cpuinfo | grep -i "model name" | head -1 | awk -F: '{print $2}'
+````
+
+````json
+{
+  "nested": { "deep": { "value": [1, 2, 3] } },
+  "escaped": "quotes \"inside\" strings"
+}
+````
+
+### Horizontal Rules vs. Table Edges
+
+---
+
+| Single col |
+|------------|
+| lonely     |
+
+---
+
+> ### Blockquote with heading
+> And a table:
+>
+> | A | B |
+> |---|---|
+> | 1 | 2 |
+>
+> And some `code` too.
+
+### Math-ish (if supported)
+
+Euler: $e^{i\pi} + 1 = 0$
+
+$$
+\sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}
+$$
+
+---