Extension system prompt options API

What Changed

Added ctx.getSystemPromptOptions() method for extensions to inspect base system prompt inputs including: custom prompt, active tools, tool snippets, prompt guidelines, appended system prompt, working directory, loaded context files, and loaded skills. Returns BuildSystemPromptOptions object.

Operator Implication

Extension developers can now introspect system prompt configuration at runtime. Enables extensions to adapt behavior based on active tools, context, and prompt settings.

Receipt

• Commit 8216cca 'Add system prompt options to extension commands' adds ctx.getSystemPromptOptions() returning base prompt inputs for extensions