fix: -t draws the (others) row out of size order

[VXNCXNX]

With -t, the aggregated (others) row is appended after the list is sorted, so when its total is larger than the rows above it the tree comes out in the wrong order and the "biggest" highlight lands on the wrong row.

Four files of 40Ki, 30Ki, 20Ki and 10Ki, shown with -t -n 2:

before    64Ki   ┌── (others)
          40Ki   ├── .bin          <- 40Ki drawn below 64Ki
         104Ki ┌─┴ (total)

after     40Ki   ┌── .bin
          64Ki   ├── (others)
         104Ki ┌─┴ (total)

The after order matches how dust draws a normal listing, where the largest sits nearest the total. The list is re-sorted once the (others) node has been pushed, inside the branch that creates it, so output without an (others) row is unchanged.

Test added in src/filter_type.rs; removing the sort fails it. cargo test passes, 33 plus 8 plus 31 plus 4. cargo fmt --check clean; the 4 clippy warnings in tests/ are pre-existing and identical on an unmodified checkout.

AI disclosure: written with Claude Code. I ran the binary before and after and checked the mutation myself.