Fix #342, #343: index sequences are part of node identity

[petlenz]

Summary

Fixes #342, fixes #343. Stacked on #388.

Two nodes stored index sequences but inherited base-class hash/equality that ignore them — the same bug class #266 fixed for inner_product_wrapper:

Before	After
permute_indices(T,{2,1,3}) == permute_indices(T,{1,3,2}) → true; difference → 0{3}	distinct; stays symbolic
dot_product(A,{1,2},B,{1,2}) == dot_product(A,{1,2},B,{2,1}) → true (A:B ≡ A:Bᵀ); sum → 2*dot(...), difference → 0	distinct; no false merge/cancel

Design

• update_hash_value overrides fold the sequence(s) into the hash (the inner_product_wrapper hash excludes contraction indices #266 pattern, plus the m_hash_value = 0 reset that inner/outer_product_wrapper update_hash_value never resets m_hash_value — recompute yields a different hash #372 notes the inner_product_wrapper hash excludes contraction indices #266 version lacks — the new overrides don't inherit that latent bug).
• Non-template operator==/operator< friends compare sequences before delegating to the base comparison (win overload resolution over the base templates used by equals_same_type/less_than_same_type).
• The evaluator half of the t2s node (ignores sequences at evaluation, rank≠2 throws) is t2s evaluator ignores tensor_inner_product_to_scalar index sequences — dot(A,{1,2},B,{2,1}) evaluates as A:B; rank-1/rank-4 contractions throw #353 — separate branch.

Tests

2 new IndexSequenceIdentity lock-in tests (hash + equality + no-false-cancel + exact-match-still-cancels, both nodes). Full suite: 2428/2428 pass. gcc-14 -Werror syntax check clean.