v0.10.2

HTTP transport state-serialization hardening (continuation tokens over the stateless HTTP transport). Re-cut of 0.10.1 (whose tag was published immutable before a javadoc fix).

• Round-trip producer state by field rather than getters, plus an Arrow Schema codec (IPC message round-trip) so state objects can hold a Schema directly.
• Handle java.time fields in state (jsr310).
• Write empty dictionaries for zero-row token/continuation batches so dict-encoded (ENUM) schemas render; carry the input batch's dictionaries through to the exchange response.
• Self-describing state tokens: prefix the concrete state class name so /exchange resolves the right type even when many state types are multiplexed through one wildcard init RPC (VGI).
• VGI_STREAM_DEBUG logs otherwise-swallowed stream-handler exceptions server-side.

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