feat: Add configurable permission detail display for tool calls

[lazyskulptor]

Summary

Add support for displaying tool-specific details (like eval-elisp expressions) in permission dialogs with syntax-highlighted code fences.

Problem

When OpenCode (or other agents) sends tool calls like emacs_eval-elisp, the permission dialog only shows the tool title without the actual expression being evaluated. This makes it hard for users to understand what code will be executed.

The previous fix (#619) addressed the timing issue of rawInput arriving late, but didn't add support for displaying the expression field specifically.

Solution

Introduce configurable mappings to extract and display meaningful details from rawInput:

New defcustoms

1. agent-shell-permission-detail-field-map: Maps tool call titles to their rawInput field names

   • Default: emacs_eval-elisp → expression, org-search → match, org-roam-search → query

2. agent-shell-permission-language-map: Maps tool call titles to code fence languages

   • Default: Bash → console, emacs_eval-elisp → elisp

Heuristic fallback

When no mapping exists, the code extracts the longest string value (≥20 chars, not a URL) from rawInput as a fallback.

Example

Before:

⚠ Tool Permission ⚠
emacs_eval-elisp

After:

⚠ Tool Permission ⚠
```elisp
(+ 100 200 300)

## Changes

- Add `agent-shell-permission-detail-field-map` defcustom
- Add `agent-shell-permission-language-map` defcustom  
- Add `agent-shell--extract-permission-detail` function
- Add `agent-shell--extract-detail-from-raw-input` function
- Add `agent-shell--get-permission-language` function
- Update `agent-shell--permission-title` to use the new functions

## Backward Compatibility

- Existing `command` and `filepath` handling is preserved
- Bash commands continue to work with `console` code fence
- The `(equal (map-elt tool-call :kind) "execute")` check is kept for tools without language mapping

Fixes #617

[xenodium]

Thanks for the PR.

I'm a little worried about mering further logic (specially MCP-specific) into the permission dialog. Couldn't this be fixed by getting the MCPs to report details outside of rawInput? Maybe fix there instead?

[xenodium]

I've extended #632 in 718d338 which is more on the generic side of things. Please try that.