feat: add configurable table styles (markdown, boxDrawing, doublePipe)

[bquenin]

Summary

Adds configurable table styles, addressing review feedback to not make box-drawing the only option.

• Strategy pattern: Each style provides a renderTable() function, cleanly separating parsing from rendering
• createBorderedStyle(chars) factory: All bordered variants (boxDrawing, doublePipe) are generated from a character map — adding a new bordered style is a single function call
• Default to standard markdown: Existing behavior is preserved out of the box
• OPENCODE_TABLE_STYLE env var: Set to markdown (default), boxDrawing, or doublePipe
• Shared parseTable(): Style-independent parsing extracted into its own function
• formatSeparatorCell restored: Markdown style uses the original separator logic from main

Available styles

markdown (default):

| Name   | Age | City     |
| ------ | --- | -------- |
| Alice  | 30  | New York |
| Bob    | 25  | London   |

boxDrawing:

┌────────┬─────┬──────────┐
│ Name   │ Age │ City     │
├────────┼─────┼──────────┤
│ Alice  │ 30  │ New York │
│ Bob    │ 25  │ London   │
└────────┴─────┴──────────┘

doublePipe:

╔════════╦═════╦══════════╗
║ Name   ║ Age ║ City     ║
╠════════╬═════╬══════════╣
║ Alice  ║ 30  ║ New York ║
║ Bob    ║ 25  ║ London   ║
╚════════╩═════╩══════════╝

Extensibility

Adding a new bordered style is a one-liner:

myStyle: createBorderedStyle({ topLeft: "╭", horizontal: "─", ... })

Closes #7

[franlol]

Love the idea, this makes the tables look much nicer!

I agree that we shouldn’t force a single style by default, instead, a configuration option would be so good.

But the implementation should be scalable, so adding more styles later (like a "doublePipe" option using double‑line box characters) is straightforward:

╔═══════╦═════╦══════════╗
║ Name  ║ Age ║ City     ║
╠═══════╬═════╬══════════╣
║ Alice ║ 30  ║ New York ║
║ Bob   ║ 25  ║ San Diego║
╚═══════╩═════╩══════════╝

Can you adjust the PR to add this as a style option , with the default one set to the standard markdown, and with a structure that makes extending it easy? That’ll give us flexibility without locking in one aesthetic.

Thanks!

[bquenin]

Hey @franlol — I've reworked this based on your feedback. Here's what changed:

• Default is now standard markdown (| --- | tables), so existing behavior is preserved
• Style is configurable via the OPENCODE_TABLE_STYLE env var (markdown, boxDrawing, doublePipe)
• Extensible structure — adding a new bordered style is a single createBorderedStyle({ ... }) call
• Parsing is separated from rendering via a strategy pattern, so styles don't leak into each other

Let me know what you think!