Match PDO MySQL lastInsertId() behavior in edge cases

Problem

WP_MySQL_On_SQLite::lastInsertId() snapshots SQLite's last row ID, but SQLite and PDO MySQL differ in several cases:

• A multi-row insert returns SQLite's last generated ID; PDO MySQL returns the first.
• An insert into a table without AUTO_INCREMENT can expose a SQLite row ID; PDO MySQL returns "0".
• A fully ignored insert can expose a stale or advanced SQLite ID; PDO MySQL returns "0".

The PDO coverage work in #471 handles initialization, operation resets, and isolation from internal SQLite writes, but not these differences.

Expected behavior

Derive the ID from the user-issued MySQL INSERT or REPLACE operation rather than directly exposing SQLite's connection-level last row ID.

Add coverage for single-row, multi-row, explicit-ID, non-auto-increment, ignored, replace, and duplicate-key-update cases.

Start with WP_MySQL_On_SQLite::lastInsertId() and the PDO coverage work referenced in #471. Add coverage for the listed INSERT and REPLACE cases, then verify the returned IDs match PDO MySQL behavior rather than SQLite's connection-level last row ID.