The Vulcanus cliff-blocking tile set has four definitions and nothing checks they agree

[wormeyman]

The set of Vulcanus tiles that block cliff placement - lava and lava-hot -
is written out in four places, with no shared definition and nothing asserting
the four agree.

where	form
src/noise/cliffs/cliffCatalog.ts:447	new Set(["lava", "lava-hot"])
crates/fmw-noise/src/cliffs/vulcanus_fields.rs:220	matches!(tile, VulcanusTile::Lava | VulcanusTile::LavaHot)
crates/fmw-noise/src/fixtures.rs:3632	is_lava, the same enum match again
crates/fmw-noise/src/fixtures.rs:3633	want_lava, by NAME: name == "lava" || name == "lava-hot"

The last two sit on adjacent lines and say the same thing in two different
vocabularies, which is what makes this worth a ticket rather than a shrug: the
string form and the enum form can drift apart without either file changing.

Why it is not currently wrong

The values agree today; that was checked. The risk is entirely about what
happens when the set changes. vulcanus_fields.rs:195 records that the set was
established by measurement - "Switching lava and lava-hot out of the tile
autoplace category and regenerating is what established the set, not a reading
of tile_collision_masks" - so a future tile that blocks cliffs would be found
the same way, and would then need editing in four places, one of which is a
string literal in a fixture helper.

Shape of a fix

One definition per side, and a test that the two sides agree:

• Rust: a const or an is_cliff_blocking(VulcanusTile) -> bool in
  tiles/vulcanus_catalog.rs, used by vulcanus_fields.rs and by both helpers
  in fixtures.rs. The name-based want_lava should go through
  VulcanusTile's existing name mapping (vulcanus_catalog.rs:95) rather than
  matching strings of its own.
• The TypeScript set already has one home, cliffCatalog.ts, as of Rehome the symbols the dead set still owes surviving code (#227) #361.
• A parity assertion that the Rust set and VULCANUS_CLIFF_BLOCKING_TILES hold
  the same names, so a change on one side that misses the other is loud.

Found while auditing #227's phase 7; the TypeScript side moved to
cliffCatalog.ts in #361 and is not affected by the deletion.