Bomb planted — *where*: the message line and the kill feed name the place, in the map's own words #188

Pushed.

The plant message now names the place it stands in, resolved with placeAt(world.map, bomb.pos) at the moment of the plant (not per tick): Bomb planted — B site instead of the old The bomb has been planted at B. Falls back to plain Bomb planted if placeAt can't resolve a name for some reason.

I left the defuse message and the drop-in-the-open case alone, with a comment explaining why each time: a defuse happens right where the plant line already named, and a drop already gets its place from the kill feed entry above it, so naming it twice would tell the person nothing new. Neither observe.ts, plan.ts, nor the bot policy inputs changed — this is purely the HUD's message line.

Tests: a bomb planted on each site of each map asserts the exact message text via placeAt, one test confirms the line is written once per plant even when use is held past the plant finishing, and one confirms a round restart replaces it with the round's own result. README's Playing section now says the plant puts a line on the message log naming the site. bun run check (tsc + full test suite, 736 tests) passes.

Closes #174