Adds VaultStore.to_dict/from_dict on top of Phase A's array codec. Persists the
versors (bit-exact via the codec), metadata, store_count, reproject_interval,
and max_entries; rebuilds the derived _exact_index on load and leaves the lazy
_matrix_cache None.
Bright line (vault/store.py is a CLAUDE.md forbidden normalization site): the
load path performs NO reprojection / normalization / repair — it restores the
exact persisted bytes (already null-projected at their last live reproject
boundary) and rebuilds only the pure index. Proven by a test asserting the
restored versors are BIT-IDENTICAL to the originals (a reproject would change
them via null_project) and that exact CGA recall — including the score==inf
exact-match short-circuit — is identical after a save/load cycle.
5 new tests + INV-02 (normalize-not-called-outside-gate) + all vault tests pass
(116 passed). Part of the A->E Shape B+ scope (Phase B).
