fix(api): limit help description width to avoid string.format error

[epheien]

Summary

Fixes a bug where running /help command in Opencode with position='current' configuration triggers an error:

Error executing vim.schedule lua callback: ...opencode.nvim/lua/opencode/api.lua:510: invalid option '%-131' to 'format'

Root Cause

Lua's string.format function has a maximum width limit of 99 characters for format specifiers. When position='current' is configured, the output window opens in the current window with a very large width (e.g., 161 characters). The code calculates max_desc_length = window_width - 30, which can exceed 99 and trigger the "invalid conversion specification" error.

Fix

Cap max_desc_length at 90 characters to stay safely under the 99-character limit:

local max_desc_length = math.min(90, vim.api.nvim_win_get_width(state.windows.output_win) - 30)

Testing

• Tested with position='current' configuration
• /help command now works correctly without errors
• Tested with various window sizes