perf(remote): Skip ILookup in read error detection walk

[chickendreanso]

• execute-read now detects per-path errors by walking the matcher's realized :val instead of the raw data, so ILookups are invoked once per accessed key in the pattern
• Fold error detection, var filtering, and all-covered classification into one pass via new private classify-vars; replaces detect-read-errors and classify-result
• Drop error-covered bindings from partial-success read responses — previously leaked as nil, or as the error map itself when a var's path landed exactly on the error
• Match-failure branch reuses the already-computed errs list for the "covered by existing error?" check, avoiding a separate pass over the error map
• Update remote/CLAUDE.md to describe the single-pass detection
• Bump remote to 0.1.4 with matching changelog entry