Add wpdb fallback for wp db query, wp db import, wp db drop, and wp db reset when mysql/mariadb binary is unavailable

[Copilot]

Several wp db commands currently require the mysql/mariadb CLI binary, causing failures with drop-in database engines (HyperDB, custom drivers) or environments where the binary simply isn't installed. This PR adds automatic fallback to WordPress's $wpdb for all relevant commands.

Changes

src/DB_Command.php

• is_mysql_binary_available() — probes for the mysql/mariadb binary via /usr/bin/env <binary> --version; result is statically cached
• maybe_load_wpdb() — loads the minimal WordPress files needed for $wpdb (load.php, compat.php, plugin.php, functions.php, class-wpdb.php), includes any wp-content/db.php drop-in (HyperDB et al.), and falls back to creating a plain wpdb instance with wp-config.php credentials + $table_prefix
• run_query() — now checks binary availability at the top and, when absent, routes through maybe_load_wpdb() + $wpdb->query() instead of invoking the mysql CLI. This covers drop and reset.
• query() — after the existing SQLite branch, checks binary availability and routes to the new wpdb path when absent via wpdb_query()
• wpdb_query() — executes arbitrary SQL via $wpdb; mirrors the mysql-path behaviour (row-count reporting for DML, formatted tabular output for SELECT, --skip-column-names support)
• import() — when the mysql binary is unavailable, reads the SQL file (or STDIN) and delegates to wpdb_import()
• wpdb_import() — executes a SQL dump through $wpdb statement-by-statement, applying the same autocommit=0 / unique_checks=0 / foreign_key_checks=0 … COMMIT optimizations as the mysql path (unless --skip-optimization is passed)
• split_sql_statements() — splits a SQL string into individual statements using a state-machine parser that correctly handles single-quoted strings, double-quoted strings, -- line comments, and /* */ block comments

features/db-query.feature

Added a @require-mysql-or-mariadb scenario that shadows the real binary with a fake exit 127 script via PATH prepending, then asserts the query succeeds and the debug message confirms the fallback was taken.

features/db.feature

Added @require-mysql-or-mariadb scenarios for wp db drop and wp db reset that shadow the binary with a fake exit 127 script and assert each command succeeds via the wpdb path (verified via the Query via wpdb: debug line).

features/db-import.feature

Added a @require-mysql-or-mariadb scenario that exports a real SQL dump first, then shadows the binary and re-imports it, asserting success and the MySQL/MariaDB binary not available, falling back to wpdb for import. debug message.

Note: wp db create is not covered by the wpdb fallback because wpdb requires the target database to already exist in order to establish a connection — a from-scratch create (no DB yet) cannot be handled via vanilla wpdb.

[codecov]

Codecov Report

❌ Patch coverage is 35.81081% with 95 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/DB_Command.php	35.81%	95 Missing ⚠️

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