v0.7.2

Another patch primarily cleaning up support for Opus 4.5:

Model improvements:

• Opus 4.5 uses Anthropic's new effort parameter instead of thinking token budget
• Only show "1M Context" button for Sonnet 4.5

Also:

• Fixed bug where web/remote terminals weren't spawning in Electron
• Adds new web_fetch tool so Mux agents can read URLs