feat(connect): make auto-connect to user's Chrome the default behavior

- Auto-connect is now ON by default (was opt-in via --auto-connect)
- Added --launch/--new flags to explicitly start a fresh browser
- CI environments (CI env var) automatically use --launch mode
- Friendly error message with platform-specific Chrome relaunch guide
- Mentions Chrome 144+ runtime CDP toggle (chrome://inspect)
- --cdp and --provider flags implicitly disable auto-connect
- AGENT_BROWSER_NO_AUTO_CONNECT=1 to disable, AGENT_BROWSER_FORCE_LAUNCH=1 to force

Track 3 of native-stealth migration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/output.rs

@@ -3076,8 +3076,9 @@ Authentication:
                              (or AGENT_BROWSER_SESSION_NAME env)
   --state <path>             Load saved auth state (cookies + storage) from JSON file
                              (or AGENT_BROWSER_STATE env)
-  --auto-connect             Connect to a running Chrome to reuse its auth state
-                             Tip: agent-browser --auto-connect state save ./auth.json
+  --auto-connect             Connect to a running Chrome (DEFAULT - shares cookies/sessions)
+                             Tip: enable CDP via chrome://inspect/#remote-debugging
+  --launch, --new            Launch a fresh browser instead of connecting to existing
   --headers <json>           HTTP headers scoped to URL's origin (e.g., Authorization bearer token)
 
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