Feature: Browser-based (SSO) authentication + session keep-alive

[cwbr]

Summary

Adds browser-based SSO authentication (Kerberos, SAML, Keycloak) and automatic session keep-alive to prevent idle timeouts — especially useful for cookie/browser-auth sessions.

Browser-Based SSO Authentication

Opens a Chromium browser for SSO login, captures session cookies, and passes them to the ADT client. Supports SAML, Kerberos, Keycloak, and form-based login flows.

New files:

• browser_auth.go — Browser login via chromedp (312 lines)
• browser_auth_test.go — Unit tests (100 lines)

New CLI flags:

Flag	Env Variable	Description
--browser-auth	SAP_BROWSER_AUTH	Open browser for SSO login
--browser-auth-timeout	SAP_BROWSER_AUTH_TIMEOUT	SSO login timeout (default: 120s)
--browser-exec	SAP_BROWSER_EXEC	Path to Chromium browser (default: auto-detect)
--cookie-save	SAP_COOKIE_SAVE	Save cookies to file for reuse with --cookie-file

Usage:

vsp --url https://host:44300 --browser-auth
vsp --url https://host:44300 --browser-auth --cookie-save cookies.txt

Session Keep-Alive

Background goroutine sends periodic HEAD requests to /sap/bc/adt/core/discovery to keep the SAP session alive during idle periods. Refreshes the CSRF token as side effect.

Flag	Env Variable	Default	Description
--keepalive	SAP_KEEPALIVE	5m	Keep-alive interval (0 to disable)

Changed files:

• http.go — Added Ping() method on Transport
• client.go — Added StartKeepAlive()/StopKeepAlive() with goroutine lifecycle management
• server.go — KeepAliveInterval config field, auto-start in NewServer()
• main.go — CLI flag, env var binding, verbose logging

Documentation

Updated configuration tables in README.md and CLAUDE.md with all new flags.

Dependencies

Added github.com/chromedp/chromedp + github.com/chromedp/cdproto for headless browser control.

[cwbr]

Solves #30