Add CFTC COT data integration with foundation data model layer

- New extraction package (cftc_cot): downloads yearly Disaggregated Futures ZIPs
  from CFTC, etag-based dedup, dynamic inner filename discovery, gzip normalization
- SQLMesh 3-layer architecture: raw (technical) → foundation (business model) → serving (mart)
- dim_commodity seed: conformed dimension mapping USDA ↔ CFTC codes — the commodity ontology
- fct_cot_positioning: typed, deduplicated weekly positioning facts for all commodities
- obt_cot_positioning: Coffee C mart with COT Index (26w/52w), WoW delta, OI ratios
- Analytics functions + REST API endpoints: /commodities/<code>/positioning[/latest]
- Dashboard widget: Managed Money net, COT Index card, dual-axis Chart.js chart
- 23 passing tests (10 unit + 2 SQLMesh model + existing regression suite)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

uv.lock

@@ -9,6 +9,7 @@ resolution-markers = [
 [manifest]
 members = [
     "beanflows",
+    "cftc-cot",
     "materia",
     "psdonline",
     "sqlmesh-materia",
@@ -344,6 +345,17 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/db/3c/33bac158f8ab7f89b2e59426d5fe2e4f63f7ed25df84c036890172b412b5/cfgv-3.5.0-py2.py3-none-any.whl", hash = "sha256:a8dc6b26ad22ff227d2634a65cb388215ce6cc96bbcc5cfde7641ae87e8dacc0", size = 7445, upload-time = "2025-11-19T20:55:50.744Z" },
 ]
 
+[[package]]
+name = "cftc-cot"
+version = "0.1.0"
+source = { editable = "extract/cftc_cot" }
+dependencies = [
+    { name = "niquests" },
+]
+
+[package.metadata]
+requires-dist = [{ name = "niquests", specifier = ">=3.14.1" }]
+
 [[package]]
 name = "charset-normalizer"
 version = "3.4.4"