Standardize query builder syntax across Rust, TypeScript, and C#

[cloutiertyler]

Description of Changes

Standardizes the query builder API across all three language SDKs (Rust, TypeScript, C#) for consistency.

Rust:

• Rename Query struct to RawQuery, make Query a trait with fn into_sql(self) -> String
• All builder types (Table, FromWhere, LeftSemiJoin, RightSemiJoin) implement Query<T> trait
• Views can return -> impl Query<T> instead of specifying exact builder types
• The #[view] macro auto-detects impl Query<T> and rewrites to RawQuery<T>
• Add Not variant to BoolExpr with .not() method

TypeScript:

• Add ne() to ColumnExpression
• Refactor BooleanExpr to BoolExpr class with chainable .and(), .or(), .not() methods
• Make builders valid queries directly (.build() deprecated but still works)
• Deprecate from() wrapper — use tables.person.where(...) directly
• Merge query export into tables so table refs are also query builders
• Add subscription callback form: subscribe(ctx => ctx.from.person.where(...))
• Unify useTable with query builder syntax; deprecate filter.ts

C#:

• Add Not() method to BoolExpr<TRow>
• Add IQuery<TRow> interface implemented by all builder types (Table, FromWhere, LeftSemiJoin, RightSemiJoin, Query)
• Add ToSql() to all builder types so .Build() is no longer required
• Update AddQuery to accept IQuery<TRow> instead of Query<TRow>

API and ABI breaking changes

• Rust: Query<T> is now a trait (was a struct). The struct is renamed to RawQuery<T>. This is a breaking change for any code that used Query<T> as a type directly.
• TypeScript: BooleanExpr is now a BoolExpr class (was a discriminated union type). The query export is deprecated in favor of tables.
• C#: AddQuery now accepts Func<QueryBuilder, IQuery<TRow>> instead of Func<QueryBuilder, Query<TRow>>. Existing .Build() calls still work since Query<TRow> implements IQuery<TRow>.

Expected complexity level and risk

3 — Changes touch multiple language SDKs and codegen, but each individual change is straightforward. The Rust macro rewrite for impl Query<T> detection is the most complex piece. All existing .build()/.Build() calls continue to work.

Testing

• cargo test -p spacetimedb-query-builder — 16/16 tests pass
• cargo check -p spacetimedb — clean, no warnings
• cargo check on views-query, views-sql, views-basic, views-trapped smoketest modules — all clean
• cargo test -p spacetimedb-codegen codegen_csharp — snapshot updated, passes
• npm test (TypeScript) — 101/101 tests pass
• C# QueryBuilder tests — new tests for Not(), IQuery<T> interface
• CI passes