Add expression trie BindingSpace access

[MesTTo]

Adds expression-trie access for BindingSpace plans.

The branch adds a BindingAccessPlan::Pattern access path. A pattern factor builds a typed expression trie from the current sidecar snapshot, retrieves candidate facts by grounded prefix, exact-filters those candidates, and projects matched user slots into a BindingRelation. It also adds PatternProjection validation and counters for indexed facts, candidate facts, exact pattern checks, and matches.

Review this after both pr/mork-binding-domain-cursor and pr/mork-expression-trie-sidecar. The stack base combines those prerequisites so this PR diff is only the BindingSpace integration layer.

Validation:

• cargo +nightly-2026-06-01 test -p mork --lib binding_plan with RUSTFLAGS='-C target-cpu=native'
• cargo +nightly-2026-06-01 test -p mork --lib expression_trie with RUSTFLAGS='-C target-cpu=native'
• cargo +nightly-2026-06-01 test -p mork --lib with RUSTFLAGS='-C target-cpu=native'
• rustfmt --check on kernel/src/binding_plan.rs and kernel/src/test_sidecar_queries.rs
• jscpd on kernel/src/binding_plan.rs, kernel/src/expression_trie.rs, kernel/src/pattern_relations.rs, kernel/src/test_exprs.rs, and kernel/src/test_sidecar_queries.rs
• git diff --check
• normal diffstat matched git diff -w --stat