[jampukka]

Adds the community module that serves tiles from a PMTiles v3 archive, read in place from a local file or over HTTP range requests, through the MapTileSource and VectorTileSource SPIs. Not wired into the reference webapp. Reading only: the archive writer comes with the tile generator PR.

• PMTilesArchive
  • The opened archive: header, root directory, leaf directories and tile lookup by tile id. Leaf chains are capped at four levels.
  • Leaf directories sit in a bounded LRU (64 entries), so a leaf is read once and then reused.
  • Lengths and counts read from the archive are checked before anything is allocated.
• TileId
  • XYZ to the PMTiles Hilbert tile id and back. Directories are sorted by this id, which is what the lookup depends on.
• Directory
  • One parsed directory with find returning the entry that covers a tile id. A run length of 0 marks a pointer to a leaf directory.
• RangeReader
  • The byte access under the archive, by offset and length.
  • FileRangeReader: positional reads on one channel, so concurrent tile requests need no lock.
  • HttpRangeReader: one Range request per read.
• TileIndex / BoxedTileIndex
  • Resident index from tile id to byte location, built at startup only when pmtiles.sendfile is set. On those layers a request does no directory I/O; otherwise a tile read walks the directories.
  • BoxedTileIndex is a dense array per zoom, used only when every zoom's bounding box is at least half filled. Otherwise the sorted TileIndex serves.
• PMTilesTileSource / PMTilesVectorTileSource
  • The raster (pmtiles) and vector (pmtiles-vector) sources, sharing one config parser. Tile bytes are relayed as stored, never decoded.
• No new third-party dependency (tiles-core, slf4j-api)
  • range readers are local until: hakunapi-bytes can not be used from a Java 21 module; migration is the intent.

Behaviour:

• No change to existing modules; tiles are served only when a pmtiles or pmtiles-vector layer is configured
• Only HTTP 206 is accepted from a remote archive; a server that ignores Range and answers 200 is an error
• Range lengths and decompressed sizes are capped at 64 MiB, and a directory's entry count cannot exceed its byte length / 4
• tile_compression brotli and zstd are served with Content-Encoding: br and zstd, gzip as gzip; an archive without tile compression is served without the header
• Brotli and zstd internal compression are rejected at startup, since decoding them would need a dependency
• A tile address outside the zoom's range is an empty tile (404), not an error
• pmtiles.sendfile is accepted only for pmtiles-vector, and needs pmtiles.path; for pmtiles it fails at startup
• The configured type must match the archive: an MVT archive needs pmtiles-vector, a raster archive needs pmtiles; a mismatch fails at startup