Fix SQLite provider crashes and foreign-key error handling - #1372

Summary

Fix three failure modes in the SQLite provider that were found during query-plan-guidance runs:

• Parse schema column definitions at top-level commas only. Commas inside nested expressions, constraints, and quoted values no longer desynchronize column metadata, and schema objects whose reported columns outnumber parsed definitions no longer cause an ArrayIndexOutOfBoundsException.
• Use getRandomTableOrBailout when generating DELETE statements so SQLancer skips the action when no writable table is available instead of selecting from an empty list.
• Treat [SQLITE_CONSTRAINT_FOREIGNKEY] as an expected insert/update error instead of reporting a valid SQLite constraint failure as an assertion failure.

Regression tests

• Cover nested and quoted commas in schema definitions.
• Reconstruct a schema containing a view without an explicit column list; this test reproduces the original ArrayIndexOutOfBoundsException on the parent commit.
• Verify that DELETE generation bails out when only a view is available.
• Verify that SQLite foreign-key constraint errors are recognized as expected.

Testing

• mvn -q -Dtest=sqlancer.sqlite3.TestSQLite3Errors,sqlancer.sqlite3.gen.dml.TestSQLite3DeleteGenerator,sqlancer.sqlite3.schema.TestSQLite3Schema test
• mvn -q -DskipTests verify