Caller-specific context template overrides for ctx init

[bilersan]

Summary

Different AI tools have different capabilities, APIs, and conventions. When ctx init creates the .context/ directory, the AGENT_PLAYBOOK.md should be tailored to the calling tool — a VS Code Copilot Chat extension needs different guidance than Claude Code running in terminal.

Currently, ctx init always emits the same generic AGENT_PLAYBOOK.md regardless of the calling tool. There is no mechanism for callers to identify themselves or receive customized output.

Proposed Solution

Add a --caller flag to ctx init that lets the calling tool identify itself:

ctx init --caller vscode    # VS Code extension calls this
ctx init --caller claude    # Claude Code (default, no flag needed)
ctx init                    # Generic templates (backward compatible)

When --caller is set, a new TemplateForCaller(name, caller) function checks overrides/<caller>/<template>.md for a caller-specific version before falling back to the default template. This keeps the default behavior unchanged while allowing tool-specific customization.

VS Code Override

The first override is overrides/vscode/AGENT_PLAYBOOK.md — a VS Code-optimized playbook covering:

• Workspace API patterns and file system conventions
• Extension lifecycle and activation events
• Copilot Chat participant conventions
• VS Code-specific debugging workflows
• Webview and TreeView patterns

[bilersan]

Superseded by PR #36 which includes the caller-specific context template override feature (--caller flag + TemplateForCaller).