refactor(tools): drop the unused guard API from this PR

safeUrlPath, safeOpaqueUrlSegment and SafeUrlPathOptions had zero call
sites -- 469 lines of unused API in a docs-generator change, including an
allowEmptySegments flag whose own TSDoc documents a host-takeover footgun
('//evil.com' under new URL(relative, base)). They belong with the ~693
traversal call sites that use them, where they can be reviewed against real
usage.

What stays is the part with 44 live consumers: safeUrlPathSegment now
accepts number and bigint. Staging already rejected every non-string, so
this only widens acceptance -- a differential over 87 real call-site values
shows 87 identical, 0 differing.

Also: encodeURIComponent throws an unnamed URIError on a lone surrogate,
which JSON.parse accepts, so a truncated emoji lost the param name the file
claims as its invariant. And the exponential rejection told tiny values like
1e-7 they were 'too large' when they round-trip exactly; the rejection is
right -- a path segment should not rewrite 0.0000001 into other text -- but
the stated ground was not.

Author: waleedlatif1