fix(grid): consistent sorting for columns with mixed primitive types

[Blankll]

Problem

The #171 sorting implementation resolves the comparison kind per cell (resolveSortKind on every comparison). On columns holding mixed primitives — routine on SQLite, whose dynamic typing mixes integers, booleans and strings in one column — this breaks two ways:

• the comparator flips kind between passes → unstable order
• resolveSortKind inspected only the left value → compare(a,b) !== -compare(b,a) → asymmetric comparator

Fix

Kind is now resolved once per column (resolveColumnKind):

• the declared column type wins outright (integer → numeric, …)
• without a usable declaration, the highest-precedence kind present in the column is used — number → boolean → date → string; strings are never date-sniffed
• sortRowsByState resolves kinds per sorted column and reuses them across passes
• everything else from feat(grid): client-side sorting for primitive result columns #171 is preserved: NULL-after-values ordering, non-primitive column exclusion, boolean/number/date coercers, stable ties

Test plan

• gridSort.test.ts — 24 passed, incl. new cases: untyped number+string column sorts by one fixed kind; comparator symmetry on mixed columns; declared type wins over value kinds
• vue-tsc --noEmit + eslint clean