Cut allocation in GeoPackage reads: one row at a time, zero-copy geometry

[jampukka]

This is purely a performance optimization of the hakunapi-source-gpkg read path: it lowers allocation and GC pressure per feature. Output is unchanged and no new configuration is added.

• Row-at-a-time reading (concept, not a class)
  • One row per hasNext() into a single reused container, instead of batches of 250. SQLite runs in-process, so a batch saves no round trips, and it keeps every row's values (geometry byte[] above all) reachable until the batch is consumed.
  • Precondition for the zero-copy geometry below: that buffer is only valid until the cursor advances.
• Zero-copy geometry access
  • A geometry blob is read through a direct ByteBuffer over SQLite's own memory instead of a new byte[] per feature. The buffer, the HakunaGeometryGPKG built on it and the ValueProvider are all valid only until the next hasNext().
• ResultSetFeatureStream
  • Streams the query's rows as above. Owns the statement, result set and connection, and closes them.
• ResultSetValueProvider
  • Still the JDBC-backed provider. isNull asks the column's storage class and builds no value, and getHakunaGeometry uses SqliteBlobReader when one is available.
• SqliteBlobReader (reflection)
  • Obtained once per query from the PreparedStatement. Null when the sqlite-jdbc internals it needs are not found or the statement is not sqlite-jdbc's, in which case getBytes is used.
• SqliteColumnType
  • Reads the current row's storage class from the driver's column_type, which is zero-based unlike JDBC's one-based indexes. Unwraps the statement because the connection pool hands out a proxy. Null when the statement is not SQLite's, in which case isNull uses getObject.
• hakunapi-source-postgiskeeps its own copy ofBufferedResultSet`.
• SqliteBlobReader falls back to getBytes only when its reflective lookups fail, not when a sqlite-jdbc upgrade changes what those internals do. SqliteColumnType compiles against org.sqlite.core, so an incompatible upgrade fails at build time, but a change in what the calls return is not detected.