[TASK] ProjectMarker.predicate case

[kirich1409]

Context

ProjectMarker.predicate(id:_:) invokes closure per directory. Used by Python-style multi-marker scenarios (any of pyproject.toml, setup.py, requirements.txt).

Acceptance criteria

• Predicate closure called and results grouped by marker id.
• Synthetic Python-style marker test passes.

Files to touch (estimate)

best-effort estimate; agent refines during implementation

Implementation notes

n/a

Dependencies

• Blocked by [TASK] FastWalkerImpl via getattrlistbulk (P1) #58

Safety checklist

See .github/ISSUE_TEMPLATE/task.yml — tick applicable invariants in the issue if any destructive path is touched.

Definition of Done

• Acceptance criteria satisfied and verifiable
• Tests added or updated
• No build / lint / test regressions
• Self-review against research-report invariants
• Code review approved