Relative/absolute path support in uses/includes

• Type: feature
• Status: done
• Owner: claude
• Opened: 2026-06-07 (manual request)

Problem

The unit resolver currently only handles unit names (identifier-based lookup). It does not support relative paths (uses '../lib/foo') or absolute paths in uses or {$include} directives.

Desired Behaviour

• uses './subdir/myunit' or uses '../shared/util' should resolve relative to the file containing the directive.
• Absolute paths (uses '/opt/libs/thing') should work as-is.
• Extension may be omitted (compiler infers .pas).
• Existing identifier-based resolution continues to work unchanged.

Scope

• Extend the unit/include resolver to accept path separators.
• Normalise paths (collapse .., handle trailing slash edge cases).
• Emit clear error when a path-based reference cannot be found.

Acceptance

A test program using a relative-path uses compiles and links correctly.

Log

• 2026-06-07 — ticket opened from user note.
• 2026-06-10 — delivered. Path-form uses './sub/unit' (quoted string in the uses list) resolves relative to the directive's file via the new CurUnitDir global (saved/restored per nested unit parse); absolute paths as-is; NormalizePath collapses ./..; extension inferred (.pas then .pp) or explicit .pas/.pp/.c/.h; miss errors with the resolved path (the identifier-form error now names the unit too). {$include} accepts absolute paths. Dedup key remains the lowercased basename, so path-form and identifier-form of the same unit dedup together. Test: test/test_relpath_uses.pas + test/relpath/ (in make test); bootstrap fixedpoint, make test, make test-nilpy all green.
• 2026-06-10 — commit 4aa293a (feature), 8896955 (LoadFile debug-writeln cleanup found en route).