Add metadata filtering to event store retrieval

[Silviculturalist]

Summary

• allow EventStore.iter_records to filter by metadata, cap results with an optional limit, and validate the new inputs
• expose the expanded filtering surface through StandComposite.iter_event_records so composites can forward metadata, kind, and index queries
• extend event store tests to cover metadata filtering, limit handling, and composite forwarding of the new parameters

Testing

• pip install --upgrade pip
• pip install -e '.[dev]'
• pip install -r docs/requirements.txt
• ruff check . --fix
• ruff format .
• pytest --cov=pyforestry --cov-report=xml --cov-report=html --cov-fail-under=50
• python scripts/check_changed_file_coverage.py $(git rev-list --max-parents=0 HEAD)

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https://chatgpt.com/codex/tasks/task_e_68ea913bcd688329a1b5415a571d11df