feat(core): tighten filter types per (breaking)

[0xTaneja]

Disallowing field-level logical operators in filters; only allow them at the root cross-field level. Implements #442.

changes I did :-

removed not and or from EntityFieldFilter<T>.
Root CrossFieldFilter<T> continues to support not/or.
Runtime : reject not/or/and if provided inside a single field filter.
Evaluator: correctly handles nested or and not at the cross-field level with AND semantics for regular fields.
Tests: updated all filter tests to use root-level not/or and added coverage for combined/nested cases.
Lint: cleaned up type-safe access and formatting.

Examples :-

Before:
{ name: { not: { is: "Jane" } } }
{ age: { or: [{ is: 25 }, { is: 40 }] } }

After:
{ not: { name: { is: "Jane" } } }
{ or: [{ age: { is: 25 } }, { age: { is: 40 } }] }

Notes
No server/docs/deploy changes required.
No public GraphQL filter changes in this PR; this strictly tightens local filtering semantics.

Issue
Closes #442

Checklist
[x] Tests added/updated
[x] Types updated
[x] Lint/typecheck/build pass

[nikgraf]

nice one, thanks @0xTaneja