fix: make browser command timeout configurable via config.yaml (#2801)

browser_vision and other browser commands had a hardcoded 30-second
subprocess timeout that couldn't be overridden. Users with slower
machines (local Chromium without GPU) would hit timeouts on screenshot
capture even when setting browser.command_timeout in config.yaml,
because nothing read that value.

Changes:
- Add browser.command_timeout to DEFAULT_CONFIG (default: 30s)
- Add _get_command_timeout() helper that reads config, falls back to 30s
- _run_browser_command() now defaults to config value instead of constant
- browser_vision screenshot no longer hardcodes timeout=30
- browser_navigate uses max(config_timeout, 60) as floor for navigation

Reported by Gamer1988.

hermes_cli/config.py

@@ -145,6 +145,7 @@ DEFAULT_CONFIG = {
     
     "browser": {
         "inactivity_timeout": 120,
+        "command_timeout": 30,  # Timeout for browser commands in seconds (screenshot, navigate, etc.)
         "record_sessions": False,  # Auto-record browser sessions as WebM videos
     },