* fix(gateway): honor default for invalid bool-like config values
* refactor: simplify web backend priority detection
Replace cascading boolean conditions with a priority-ordered loop.
Same behavior (verified against all 16 env var combinations),
half the lines, trivially extensible for new backends.
* fix(tools): show browser and TTS in reconfigure menu
_toolset_has_keys() returned False for toolsets with no-key providers
(Local Browser, Edge TTS) because it only checked providers with
env_vars. Users couldn't find these tools in the reconfigure list
and had no obvious way to switch browser/TTS backends.
Now treats providers with empty env_vars as always-configured, so
toolsets with free/local options always appear in the reconfigure menu.
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Co-authored-by: aydnOktay <xaydinoktay@gmail.com>
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