Preserve innermost callable containment for C# calls, local functions, and lambdas

[Widthdom]

Summary

C# containment repeatedly skips the enclosing callable and attaches nested evidence directly to the class: hundreds of calls inside block-bodied test methods collapse to QueryCommandRunnerTests, local functions such as TryReadSchemaValue skip ParseOptions, and lambdas declared inside methods also attach to the class.

Audit IDs: Q-07, G-04, and G-05. This is a current regression/follow-up to closed #233 and #4417; closed #194 and #1969 are adjacent containment work.

Expected behavior

At any source location, container assignment should prefer the innermost compatible callable range before a containing type.

PR scope

These three symptoms share callable containment/range selection and belong in one PR. Same-line compact-type edge cases outside these fixtures should be added only if the shared resolver fixes them without broadening scope.

Implementation guide for Codex 5.6 sol xhigh

• Introduce/reuse one deterministic innermost-container selector for symbol and reference assignment.
• Rank exact body containment, narrower ranges, and callable kinds ahead of types; define fallbacks for expression bodies and incomplete ranges.
• Add fixtures for block-bodied test methods, local functions, nested local functions, lambdas, expression-bodied members, and nested types.
• Verify symbols, references, callers, inspect, and impact.
• Avoid name-based repairs; run full tests and add a bilingual changelog fragment referencing C#: callers attributes expression-bodied callers (public int Wrap() => Compute();) to the enclosing CLASS instead of the individual method/property #233/Persist precise symbol/reference spans for LSP and editor formats #4417.

Acceptance criteria

• Calls are attributed to the actual test method, not the test class.
• Local functions/lambdas identify their enclosing callable.
• Top-level/type-level cases and valid nested types keep correct containers.

[Widthdom]

Work started on branch fix-issue4840.