feat(proxy): add scoped proxy configuration and docs runbooks

- add scope-aware proxy schema and runtime wiring for providers/channels/tools

- add agent callable proxy_config tool for fast proxy setup

- standardize docs system with index, template, and playbooks

src/onboard/wizard.rs

@@ -133,6 +133,7 @@ pub fn run_wizard() -> Result<Config> {
         browser: BrowserConfig::default(),
         http_request: crate::config::HttpRequestConfig::default(),
         web_search: crate::config::WebSearchConfig::default(),
+        proxy: crate::config::ProxyConfig::default(),
         identity: crate::config::IdentityConfig::default(),
         cost: crate::config::CostConfig::default(),
         peripherals: crate::config::PeripheralsConfig::default(),
@@ -356,6 +357,7 @@ pub fn run_quick_setup(
         browser: BrowserConfig::default(),
         http_request: crate::config::HttpRequestConfig::default(),
         web_search: crate::config::WebSearchConfig::default(),
+        proxy: crate::config::ProxyConfig::default(),
         identity: crate::config::IdentityConfig::default(),
         cost: crate::config::CostConfig::default(),
         peripherals: crate::config::PeripheralsConfig::default(),