Chat: add beginningOfBuffer / endOfBuffer actions for multiline prompts

Feature Request

Add two new actions to the Chat context for navigating multiline prompts:

• chat:beginningOfBuffer — jump to the first line of the current prompt
• chat:endOfBuffer — jump to the last line of the current prompt

Motivation

When writing a long multiline prompt, there is currently no way to jump directly to the first or last line. Navigation requires pressing up/down repeatedly. Terminal applications like IntelliJ built-in terminal support this natively, but Claude Code has no equivalent action to bind.

Expected behavior

Users should be able to bind keys in ~/.claude/keybindings.json:

{
"bindings": [
{
"context": "Chat",
"bindings": {
"option+up": "chat:beginningOfBuffer",
"option+down": "chat:endOfBuffer"
}
}
]
}

Current workarounds

• up/down arrows — line by line navigation only
• Ctrl+A / Ctrl+E — beginning/end of current line only