feat(geo): cross-check block heights against Mapbox building data

New Geo/tools/mapbox_buildings.py (stdlib urllib) Tilequeries
mapbox-streets-v8 / layer building at each building centroid and merges
height/min_height/type with our OSM height + source (tag > levels > guess,
reusing block_height_report.classify_height). Reports matches, close calls,
disagreements (sorted worst first), our-only and mapbox-only cases, and writes
optional JSON.

First run over 72 buildings: 58 match, 5 close, 3 disagree, 6 non-building.
- Mapbox independently classifies our roof/canopy/shelter volumes as roof,
  canopy or shelter -> corroborates the 0.1.2 finding.
- The 3 disagreements are rear building=yes/apartments structures rendering at
  our 2-level guess (6.4 m) vs Mapbox's 3.0 m.
- Every levels x 3.2 m building is ~0.6 m per 6 levels taller than Mapbox
  implies, i.e. Mapbox suggests 3.1 m per level. Recorded, not applied.

classify_height() now also treats building=canopy as a non-building volume
(found by this cross-check), with tests.

Data handling: Mapbox terms restrict persisting/redistributing their data, so
.gitignore covers Geo/raw/mapbox-cache/ and Geo/verification/*mapbox*; the tool
refuses to cache a response containing the token, and the token is never written
to the cache, report or JSON. Token comes from the ignored .env.

Also: 17 new tests (29 total) for the compare/nearest/centroid/render helpers
and the canopy rule; Geo/README inventory row; architecture 05 + architecture.md
tools table updated per the new upkeep rule.

Docs/Architecture/architecture.md

@@ -201,6 +201,7 @@ Python scripts in `Tools/` drive the content pipeline:
 | `judge_screenshot.py` | Vision-model pre-check (optional) |
 | `input_emulation.py`, `input_test.py` | OS-level virtual keyboard/mouse injection for input verification |
 | `Tools/tests/` | Stdlib `unittest` tests for the pure parts of the tools (`requirements-tools.txt`) |
+| `Geo/tools/mapbox_buildings.py` | Second height source: Mapbox `mapbox-streets-v8` building data vs our OSM heights |
 
 Source data: `Art/blender/` (`.blend` files), `Geo/` (OSM extracts, DEM, verification docs).