feat(ui): the copse and the rocky outcrop, drawn per cover class (T-1213)

D-258 invariant 2 asks the map to show the minority the orbital summary
suppressed — clearings, marsh, rock, scrub inside a cell that reads "forest" from
space. composition.rs goes to real trouble to invent it, and the conservation
harness measures it: over a District patch on Ferrath the tally is {Barren: 175,
Forest: 16209}, so 1.07% of that ground is exposed rock.

The renderer was averaging it back out. One test, `veg >= Scrub`, at one density
and one strength: Forest, Scrub and both Riparian classes drew the IDENTICAL
mark, and Barren drew none at all. A wood looked like scrub, and bare rock was
invisible by construction — on the rungs whose whole purpose is to show what the
summary hid.

Each class now has its own grammar, differing on the three axes a mark has:
density (how much of the class's ground carries it), strength (how far it moves
the base colour), and lattice (the block size marks are decided on — bigger reads
as a clump, smaller as grain). Rock LIGHTENS where everything else darkens, which
is the point rather than a flourish: bare stone catching the light is the one
cover type brighter than the ground around it, so it separates from vegetation by
sign alone and can never read as "denser plants". It gets its own ScatterField
salt so an outcrop does not preferentially land where a copse already did.

Tuned against captures, not guessed. A first pass gave Forest a 4x4 lattice at
52% density, which produced visibly axis-aligned dark SQUARES — a 4-cell block is
8 screen px at District — and read as an artefact laid over the hillshade. It
also mistook the background for a feature: Forest is 98.9% of this frame, so
marking half of it dark is not "the occasional copse", it is a second colour
layer. Pulled back to grain at a 2x2 lattice, and the occasional thing is now the
thing that catches the eye: the outcrops read as scattered pale clusters of
exposed ground, exactly the "occasional copse/tree/rocky outcropping" that was
missing.

District holds its form through the change (lum p1-p99 74.15, against 74.43
before the cover marks and 13.72 when the rung was flat).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

project.yaml

@@ -58,7 +58,10 @@ name: The Settled Reach
 # entries are still valid content — but the client step_canvas cluster is in the
 # T-1242 registry and the rule is bump-when-touched, so it moves. Cheap: one
 # round of misses against a map that now reads as terrain.
-version: 0.4.10
+# 0.4.11 — per-class cover marks (copse, thicket, rocky outcrop). Paint again,
+# not derivation; bumped because the client step_canvas cluster is in the T-1242
+# registry.
+version: 0.4.11
 repository: settled-reach