fix(query): fall back to full scan for computed properties in predicates

[mrdevrobot]

Summary

• Fixes Query predicate on a computed (get-only) property silently returns false for every document #143: predicates touching a get-only computed property (e.g. IsOpen => State != Closed) were pushed down into a BSON field lookup by property name, silently returning false for every document since no such field is ever stored.
• Added IsPersistedMember (a member is only pushed down if it's a field or a property with a setter) and gated every member-name extraction point in BsonExpressionEvaluator on it: bare bool member, Nullable.HasValue, logical NOT, .Equals(), string instance methods, static string helpers, the IN operator (both list.Contains(x.Prop) and Enumerable.Contains(list, x.Prop)), the general binary comparison path, and CompareTo.
• When a member fails the check, TryCompileBody returns null, so DocumentCollection.FetchAsync falls through to its existing full-scan + in-memory-filter strategy, which compiles the real expression tree and evaluates the actual getter correctly - matching plain LINQ-to-Objects semantics instead of silently returning wrong results.

Test plan

• Unit test: entity with a get-only bool property derived from a stored enum field; insert with the property true, assert FindAsync(x => x.ComputedProp) returns it (currently returns empty without the fix)
• Regression: existing tests for the still-covered patterns (bare bool on a real stored bool field, !x.Prop, string methods, IN, binary comparisons, CompareTo) continue to push down correctly
• dotnet build/dotnet test on BLite.Core

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Compound predicates can still partially compile (dropping the computed-property side) and be executed as Strategy 2 without an in-memory re-filter, risking incorrect query results.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR fixes incorrect query results when predicates reference get-only computed properties by preventing those members from being pushed down as BSON field lookups, so queries can fall back to the existing full-scan + in-memory evaluation path.

Changes:

• Introduces IsPersistedMember and gates all member-name-based predicate compilation paths on it.
• Causes TryCompileBody to stop compiling member-based predicates for non-persisted members, intended to trigger Strategy 3 fallback in DocumentCollection.FetchAsync.

File summaries

File	Description
src/BLite.Core/Query/BsonExpressionEvaluator.cs	Adds persisted-member gating across predicate compilation paths to avoid incorrect BSON pushdown for computed properties.

Review details

Suppressed comments (1)

src/BLite.Core/Query/BsonExpressionEvaluator.cs:711

• There are existing unit tests for BsonExpressionEvaluator, but none covering the regression scenario described in #143 (computed/get-only property used in a predicate should force a Strategy 3 fallback and still return correct results). Adding a focused test would help prevent this silently returning wrong results again (including for compound predicates like x => x.ComputedProp && x.Age > 10).

    private static bool IsPersistedMember(MemberInfo member)
        => member is not PropertyInfo { CanWrite: false };

• Files reviewed: 1/1 changed files
• Comments generated: 2
• Review effort level: Lite

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