fix: percent-encode page URLs built from file paths

build_url() escaped %, # and ? one by one, so a file name carrying any
other character that a URL path cannot hold - a space, a quote, an angle
bracket, a control character - was emitted raw and only resolved if the
host happened to serve the same byte sequence the index was built from.

Encode the URL that build_url derives from the file path with the URL
spec's path percent-encode set, leaving / alone so the separators between
path segments survive. % stays in the set, so a file literally named in
encoded form keeps pointing at the file that is on disk.

URLs supplied by the caller (data-pagefind-meta="url:...", addCustomRecord)
do not go through build_url and are untouched.

Fixes #619

pagefind/Cargo.toml

@@ -90,6 +90,7 @@ actix-web = { version = "4", optional = true }
 actix-files = { version = "0.7", optional = true }
 lexical-core = "1.0.0"
 path-slash = "0.2"
+percent-encoding = "2"
 rayon = "1.10"
 rust-patch = "0.1.3"
 typed-builder = "0.23.2"