Update Anthropic model list to include Opus 4.6 and latest model names

[thoughtfulcool]

Description

GitButler's Agents Tab is showing outdated Claude model names and is missing recently released models.

Current Models

• Sonnet 1m
• Sonnet
• Haiku
• Opus
• Opus Planning

Missing Models

• Claude Opus 4.6 (claude-opus-4-6)
• Claude Opus 4.5 (claude-opus-4-5-20251101)
• Updated Sonnet 4.5 name (claude-sonnet-4-5-20250929)
• Updated Haiku 4.5 name (claude-haiku-4-5-20251001)

Current Behavior

Even with latest Claude Code installed and configured as well as latest GitButler v0.19.1, the Agents Tab only shows the older model list. (I had hoped latest update would show new models.)

Expected Behavior

GitButler should show all current models available in Claude Code.

Suggested Fix

Update the hardcoded model list (similar to PR #7555) to include:

1. All Claude 4.x models
2. Current naming conventions from Anthropic's API (So user can tell which version is available)
3. Consider making this list dynamic or possible for user to update (after at least updating to new Feb models please)

[thoughtfulcool]

To anyone who comes across this issue and wants a quick fix, this is what I used to override the available models options (even though switching models is VERY clunky):

# Create or edit ~/.claude/settings.json
echo '{"model": "claude-opus-4-6"}' > ~/.claude/settings.json

# Or if you prefer Sonnet 4.5 with the latest name:
echo '{"model": "claude-sonnet-4-5-20250929"}' > ~/.claude/settings.json