Mock provider: lpp/references conflates puzzle symbol with a same-named op #71

Audit finding M4 — verified live.

Problem

Occurrence lookup is keyed by op name only. Two wrong results:

• Position on puzzle a while op a exists -> returns op a's declaration + solution references; the puzzle's own declaration is absent.
• Position on puzzle solo with no same-named op -> locations: [] despite the position being on a valid symbol with includeDeclaration: true.

§14.2 requires the declaration to appear in locations when requested.

Acceptance criteria

• references on a puzzle symbol returns the puzzle declaration (when includeDeclaration) and never an unrelated op's occurrences; op symbols behave as today.
• Regression test covering the same-name case + green suite.