refactor drop the unused root_path and static_prefix

Neither constant has a caller in lib, bin or test. The route table builds "/" through path_of Root, and the static prefix is spelled inline in Static_handler where it is stripped. Two spellings of a path invite the copies to diverge.

Commit
eded161a2d5626e83699b8d0b357facb2d3b2b61
Author
Claude Sonnet 4 <claude@anthropic.invalid>
Author date
Committer
Marius Peter <dev@marius-peter.com>
Committer date
lib/routes.ml
index 36e654de..2a78de87 100644..100644
@@ -25,9 +25,6 @@
25 25 | Readme of string
26 26 | Raw_file of string * string
27 27
28 Removed: let root_path = "/"
29 Removed: let static_prefix = "/static/"
30 Removed:
31 28 (* Generate URL paths for routes *)
32 29 let path_of = function
33 30 | Root -> "/"