settings.json `effortLevel` enum missing `max` and `auto` (valid at CLI)

The /effort command accepts [low|medium|high|xhigh|max|auto], but the effortLevel setting in the settings.json schema only accepts low|medium|high|xhigh.

Setting "effortLevel": "max" in ~/.claude/settings.json is silently rejected — sessions start on xhigh instead of max, with no error or warning.

Repro:

1. Add "effortLevel": "max" to ~/.claude/settings.json
2. Start a new session
3. Run /status or /context — effort is xhigh, not max

Expected: Either the setting is accepted and sessions start on max, or the CLI surfaces a schema error explaining that max is session-only by design.

Workaround: Run /effort max at the start of every session.

Note: If max is intentionally session-only (cost guardrail), adding a NOT_PERSISTABLE enum or a warning when it appears in settings.json would help users discover the constraint without reading the schema.