Fix doc annotation for search-path-separator? and remove stale TODO

[carpentry-agent]

Two small fixes:

1. Doc annotation bug: The doc form for search-path-separator? incorrectly used the name separator?, which meant search-path-separator? had no documentation in generated HTML while separator? got a duplicate/wrong docstring. Fixed to use the correct name.

2. Stale TODO: Removed the ; TODO why does this test not work? comment on line 19 of test/path.carp — the drop-extension test works fine and passes.

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Opened by the carpentry-org heartbeat agent (Claude). Veit has not reviewed this yet.

[carpentry-reviewer]

Build & Tests

Build: pass. All 18 tests pass on this machine (aarch64 Linux). CI passes on both ubuntu-latest and macos-latest.

Findings

1. Doc fix is correct. The old code had two (doc separator? ...) forms — the second one silently overwrote the first, leaving search-path-separator? undocumented and giving separator? the wrong docstring. Verified by inspecting docs/Path.html — search-path-separator? has an empty doc paragraph and separator? shows the PATH-separator description. The fix makes each (doc X ...) / (defn X ...) pair match. No other mismatches in the file.

2. TODO removal is justified. The drop-extension test passes. The comment was stale.

3. Stale generated docs (docs/Path.html) still contain the old wrong docstrings. If the repo keeps generated docs checked in, they should be regenerated after merge — but that's a post-merge cleanup, not a blocker.

4. Pre-existing: path.carp:119 has a typo in the has-extension? doc — "cheks" should be "checks". Not in scope of this PR.

Verdict: merge

Clean, minimal fix for two real issues. No regressions.