[magnusp]

Summary

Extracts foreign key shaping from LibsqlDatabaseMetaData into package-private ForeignKeyMetadata:

• raw pragma row record (PragmaRow) with per-direction factories
• fromImported / fromExported
• JDBC row record (JdbcRow)
• per-direction sort comparators (IMPORTED_ORDER, EXPORTED_ORDER)
• key-name, key-rule, and ordering helpers

The two pragma SQL strings remain in MetadataSql.

Preservation

• imported/exported index asymmetries, including the PK_FIRST_COLUMN fallback
• KEY_SEQ remains the pragma sequence plus one
• DEFERRABILITY remains importedKeyInitiallyDeferred
• nameOrEmpty for FK/PK names; getPrimaryKeys keeps the primary key name null
• primaryKeyName still matches only CONSTRAINT <name> PRIMARY KEY
• foreignKeyName reverse index rule unchanged
• exported primary key names stay blank unless the parent column set contains the column
• per-direction sort keys unchanged
• no SQL, value, order, message, test, or pom.xml change

Diff

ForeignKeyMetadata.java      | 291 ++++++++++++++++++++
LibsqlDatabaseMetaData.java  | 215 +--------------
2 files changed, 296 insertions(+), 210 deletions(-)

LibsqlDatabaseMetaData.java: 846 -> 641 lines.

Probe

Changed KEY_SEQ to the raw pragma value ((int) pragma.seq() instead of (int) pragma.seq() + 1) in both directions:

LibsqlDatabaseMetaDataTest.getImportedKeysMapsForeignKeyRowsAndNames:435 expected: 1 but was: 0
LibsqlDatabaseMetaDataTest.getExportedKeysMapsForeignKeyRowsAndNames:457 expected: 1 but was: 0
Tests run: 54, Failures: 2

Reverted; ForeignKeyMetadata.java hash matched the pre-probe value.

Lanes

Lane	Command	Result
Unit	./mvnw -pl libsql-jdbc -am test	398/398, 0 failures (codec 35/35)
Spotless	./mvnw spotless:check	pass
Conformance	./mvnw -pl libsql-conformance -am verify	272 run, 0 failures, 7 skipped, BUILD SUCCESS

Fixes #209