fix(T13261): row-identity ref probe runs no JS hash per dangling ref

[kryptobaseddev]

Summary

Fixes the review-hotfix LOW on #1888 (C1). On every fill-on open, rowIdentityFillPending's ref: probe evaluated storedRefSql, which for ac_text_hash calls the JS AC-text hash, on every NULL stored-ref row. A store with many legitimately dangling bindings paid one JS call per row on every open.

The probe now uses storedRefPresentSql, which is true exactly when storedRefSql would be non-NULL, in plain SQL:

• text_hash: acTextHash returns non-NULL iff the criterion's text is a JS string, so the probe checks (SELECT typeof(text) …) = 'text'.
• uid refs: refUidSql … IS NOT NULL, the same pure-SQL condition as before.

The fill pass still derives the values with storedRefSql.

Tests

row-identity-steady-open.test.ts adds a test for 40 bindings whose criterion is gone:

• the probe reports nothing pending and calls the hash function 0 times; a counting re-registration proves this;
• when the criterion appears, both ref: entries are reported;
• after the pass, nothing is pending.

Mutation check: with the old probe restored, the test fails on 40 hash calls.

Results: the row-identity suite passes 122/122 and tsc -b packages/core is clean. Gate 38 (--base origin/main) and gate 32 (PR mode) pass.

Task: T13261

🤖 Generated with Claude Code