fix(dispatch): suppress user hooks on internal claude text-generation

Loading user settings for auth (--setting-sources user) also loads any user-level claude hooks. Verified empirically that SessionStart and UserPromptSubmit hooks fire on the internal --print GenerateText call, which undercuts the os.TempDir()/StripGitEnv isolation and could error or cause side effects on every auxiliary generation.

Layer --settings {"disableAllHooks":true} over the user settings so all user hooks are suppressed while auth still resolves (verified: apiKeyHelper, ANTHROPIC_API_KEY, and keychain/subscription all still authenticate; a real subscription dispatch --local still generates). Extend the regression test to assert both flags.

Addresses trail #884 review finding.