feat(profile): --profile auto + stop steering users into temp-profile launches

Addresses the footgun raised in issue #1 follow-up: plain `--launch` silently
uses a temporary EMPTY profile (no cookies/login), and the connect-failure
error even recommended it — trapping agents into thinking they reused the
logged-in browser when they didn't.

- `--profile auto`: resolves to the Chrome profile last used (from Local State
  `profile.last_used`), falling back to "Default", then the first profile. So
  `--launch --profile auto open <url>` reuses real login state without naming
  the profile. (--profile <name>/Default already worked.)
- connect-failure error now recommends `--launch --profile auto` and states
  plainly that bare `--launch` is a temporary EMPTY profile — no cookies/login.
- bare `--launch` (no --profile, not CI) now prints a warning to that effect.
- README: fix Setup (relaunch with --remote-debugging-port, not chrome://inspect)
  and split Standalone mode into throwaway vs. keep-your-login (`--profile auto`).

Tests: resolve_chrome_profile("auto") prefers last_used, falls back to Default.

cli/src/main.rs

@@ -531,6 +531,18 @@ fn main() {
     let mut flags = parse_flags(&args);
     let clean = clean_args(&args);
 
+    // Loudly warn when launching a fresh browser with no profile: it gets a
+    // temporary EMPTY profile (no cookies / no login). For logged-in sites the
+    // user almost always wants --profile auto (their real Chrome profile).
+    // Skipped under CI (force_launch is implicit there and login isn't expected).
+    if flags.force_launch && flags.profile.is_none() && env::var("CI").is_err() {
+        eprintln!(
+            "⚠ --launch uses a temporary EMPTY browser profile (no cookies, no login). \
+             For logged-in sites, add `--profile auto` (or `--profile Default`) to reuse \
+             your real Chrome session."
+        );
+    }
+
     let has_help = args.iter().any(|a| a == "--help" || a == "-h");
     let has_version = args.iter().any(|a| a == "--version" || a == "-V");