fix: a coarse lot is a parcel, not a 700 m building

The unidentified slab on downtown San Francisco was the lot ladder's
own coarsest rung. Tower fill of 1.5–2.2 assembles a Salesforce-shaped
site from 40 m lots; on a 400 m lot it is a 600–880 m cube, rotated
with the district's street grid, downtown palette. The same pose on
the Bay Area board uses 40 m lots and does not show it.

Cap both axes at NEIGHBOURHOOD_LOT_METRES. Fine rungs are unchanged
because 40 m and 80 m already sit under the cap. The test that would
have named this on the first photograph now exists.

TODO.md

@@ -992,46 +992,27 @@ Two smaller things, both disclosed by their own tracks and neither blocking:
   which is why it neither helps nor hurts. The fix is finer cells there, which is
   terrain level of detail — the piece that still does not exist.
 
-## An unidentified 700 m slab stands on downtown San Francisco
+## ~~An unidentified 700 m slab stands on downtown San Francisco~~ — identified and capped
 
-Found 2026-08-24 by photographing the merged board at a close pose, not by any
-test. **Reproduce it exactly:**
+Found 2026-08-24 by photograph; named 2026-08-24 by reading instance matrices
+on the merged board at the same pose, not by walking the scene graph.
+
+It was never a mystery mesh. `DETAIL_LOT_TIERS`'s coarsest rung is 400 m, and
+tower fill of 1.5–2.2 — written to assemble a Salesforce-shaped site from 40 m
+lots — on a 400 m lot is a 600–880 m cube, rotated with `gridAngle`, downtown
+palette. The same pose on `?city=sf` uses 40 m lots and does not show it.
+
+The fill is now capped at `NEIGHBOURHOOD_LOT_METRES` (260 m). Fine rungs are
+unchanged. `blocksLotLadder.test.ts` holds the cap.
+
+The reproduction still photographs the pose:
 
 ```
 node scripts/look.mjs slab --url "/" --lat 37.7897 --lng -122.3972 \
   --standoff 2500 --at 2026-08-24T18:30:00Z --wait 11000
 ```
 
-A pale blue-grey slab, roughly 700 m square with visible thickness, rotated onto
-San Francisco's street grid, sitting on the Financial District and covering the
-buildings under it. It is the most prominent object in that frame. The same pose
-on `?city=sf` does not show it, so it is specific to the merged board.
-
-**What it is not**, each ruled out by reading the code rather than by guessing:
-
-- Not a marker. The giant marker spheres in the first photograph of this pose
-  were a separate defect, fixed in this same round (scene-unit pin constants on a
-  1,919 m board); with that fixed every sphere is correctly sized and **the slab
-  is unchanged**.
-- Not an office door glyph. `buildingGlyph.ts` is metre-correct (`1 /
-  world.metresPerUnit` horizontally, `world.metres` vertically) and the three
-  office sites are 48x42, 54x30 and 36x26 m.
-- Not a landmark. San Francisco's largest authored `footprint` is 0.0011° — a
-  200 m box, and the pack's landmarks render correctly on their own board.
-- Not the freeway corridor. `overviewLayers` withdraws it inside
-  `DETAIL_STANDOFF_M`, and no corridor ribbon is in the frame.
-- Not a port or an airport plate. The merged pack carries two ports, both in San
-  Pedro Bay, and SFO is 13 km south of a frame about 3 km across.
-- Not `office-exterior`. That is the Model X apron and it lives in the office
-  scene at 1 unit = 1 m.
-
-**How to find it**, since three attempts at a runtime probe timed out walking the
-scene graph: `__teraCamera` deliberately does not expose the scene, so add a
-temporary hook beside `lots()` in `main.ts` that traverses
-`record.handle.stageScene.scene` and **filters inside `page.evaluate`** — the
-traverse itself is fine, but returning every geometry in the board serialises
-megabytes and hangs the call. Filter to `boundingBox` width above 250 m in board
-metres and return fifteen rows. That names it in one run.
-
-It is a visual defect on the default board at a pose a visitor reaches by
-descending, and it should be fixed before the next round of imagery.
+What the original list correctly ruled out (marker, office glyph, landmark,
+corridor, port, airport, office-exterior) stays ruled out. The glyph's window
+pane thickness (`0.012` / `0.028` scene units → 23 m / 54 m on this board) is
+a separate scene-unit leftover and is not this slab.