pi-synthetic v0.13.0

7e83e5f: feat(settings): make synthetic features configurable

Add shared Synthetic feature settings with a synthetic:settings command and pi config support. Web search, usage status, quota warnings, quotas command, and subBar integration can now be enabled or disabled individually. Web search, usage status, quota warnings, and subBar polling react to settings changes live. The quotas command still requires restart to fully unload.

Add an initial v1-seed-defaults migration that writes the current defaults to disk and bumps configVersion to 1. On first load, fresh installs seed the global config automatically. A one-time notice is shown on session start pointing users to pi config and the /synthetic:settings command.
ed77440: feat(usage-status): footer status bar showing live quota usage

Add usage-status extension that displays live quota percentages (weekly credits, rolling 5h, etc.) in the footer status bar when a Synthetic model is active. Colors follow the same severity assessment as quota-warnings for consistency. Auto-refreshes every 60s and after each turn. Hides for non-Synthetic models.