[codex] Add aggregate API balance queries

[KilimiaoSix]

Summary

• add aggregate API balance query storage/RPC fields and refresh endpoint
• show balance status/actions in the aggregate API page
• add built-in generic, One API/New API panel, and custom balance query templates
• make generic balance checks fallback from /user/balance to /v1/usage
• harden web runtime probing so /api/runtime transient failures recover automatically

Notes

• custom templates are restricted to relative paths and simple dot JSON paths

Closes #163

Validation

• pnpm -C apps run build:desktop
• pnpm -C apps exec eslint src/components/modals/aggregate-api-modal.tsx
• pnpm -C apps run test:runtime
• cargo test -p codexmanager-service generic_balance_extractor_accepts_usage_balance_shape -- --nocapture
• cargo test -p codexmanager-core migrations -- --nocapture
• cargo check -p codexmanager-service
• local RPC refresh verified through the generic fallback path