Parser: WHERE clause should support OR operator

[semanticintent]

Summary

The WHERE clause supports AND chaining (fixed in v0.2.1, issue #1), but does not yet support OR.

Current behaviour

FORAGE "Example"
WHERE sector = "technology"
  OR sector = "healthcare"       -- ❌ parse error

OR is not recognised in ConditionList.

Expected behaviour

FORAGE "Example"
WHERE sector = "technology"
  OR sector = "healthcare"       -- ✅ parsed

Grammar reference

In src/parser/grammar.pegjs, ConditionList only chains via AND. Adding OR support (with appropriate precedence — AND binds tighter than OR) would complete the logical operator set.

Priority

Lower priority than WHEN AND (#3) since no published cases have needed OR yet, but worth tracking for completeness.