Add hooks system with pi.send() for external message injection

- Hook discovery from ~/.pi/agent/hooks/, .pi/hooks/, --hook flag
- Events: session_start, session_switch, agent_start/end, turn_start/end, tool_call, tool_result, branch
- tool_call can block execution, tool_result can modify results
- pi.send(text, attachments?) to inject messages from external sources
- UI primitives: ctx.ui.select/confirm/input/notify
- Context: ctx.exec(), ctx.cwd, ctx.sessionFile, ctx.hasUI
- Docs shipped with npm package and binary builds
- System prompt references docs folder

packages/coding-agent/src/config.ts

@@ -70,6 +70,11 @@ export function getReadmePath(): string {
 	return resolve(join(getPackageDir(), "README.md"));
 }
 
+/** Get path to docs directory */
+export function getDocsPath(): string {
+	return resolve(join(getPackageDir(), "docs"));
+}
+
 /** Get path to CHANGELOG.md */
 export function getChangelogPath(): string {
 	return resolve(join(getPackageDir(), "CHANGELOG.md"));