The /api/query cost guardrail (next phase) needs the same singleton
QuotaTracker so its daily-byte and concurrent-slot caps accumulate
across both /api/v2/scan and /api/query BQ-touching paths.
Move `_build_quota_tracker`, `_quota_singleton`, and `_quota_init_lock`
from app/api/v2_scan.py to app/api/v2_quota.py (the natural home; the
factory uses QuotaTracker which already lives there). Re-export the
function from v2_scan.py so the 7 test sites at tests/test_v2_scan.py
(lines 77, 118, 143, 160, 186, 208, 250) keep working without edits.
Crucially do NOT re-export `_quota_singleton` from v2_scan.py — Python
`from X import var` copies the binding at import time, so a re-exported
singleton would freeze at the initial None and never observe the
in-place mutation done inside `_build_quota_tracker()`. Re-export only
the function (which always reads the live module-global through `global`).
Mechanical refactor; no behavior change. 30 quota-related tests pass.
Replaces the BigQuery wrap-view pattern with a discovery + scoped-fetch toolkit driven by the analyst's Claude session. Adds /api/v2/{catalog,schema,sample,scan,scan/estimate}, da catalog/schema/describe/fetch/snapshot/disk-info CLI commands, sqlglot-backed WHERE validator, process-local quota tracker, agent rails skill (cli/skills/agnes-data-querying.md). BREAKING: BQ wrap views off by default — set data_source.bigquery.legacy_wrap_views=true for one cycle. Backward-compat field_validator on primary_key. Catalog cache now matches documented 300s TTL with RBAC fresh per request. Cuts release v0.14.0.
