feat(rust_snuba): Add native ClickHouse client with RowBinary support

[phacops]

Summary

Add infrastructure for using the official clickhouse crate with RowBinary format for improved insert performance. The native client is fully wired up and can be enabled per-storage via configuration.

Key Changes

• Native client infrastructure (src/strategies/clickhouse/client.rs):

  • InsertableRows trait for type-erased row insertion with type-aware batch merging
  • TypedRows<T> wrapper implementing InsertableRows for any T: clickhouse::Row
  • NativeClickhouseClient with retry logic matching HTTP client behavior

• Dual-path batch support (src/types.rs):

  • Add typed_rows: Option<Arc<dyn InsertableRows>> to InsertBatch and BytesInsertBatch
  • Type-aware merge in BytesInsertBatch::merge() preserves typed rows when types match
  • InsertBatch::from_rows_with_typed() for processors to provide both JSON and typed rows

• Native writer step (src/strategies/clickhouse/writer_v2.rs):

  • NativeClickhouseWriterStep uses native client when typed_rows available
  • Falls back to HTTP/JSON when no typed rows (backward compatibility)

• Configuration (src/config.rs, src/factory_v2.rs):

  • Add use_native_client: bool option to ClickhouseConfig
  • Factory conditionally creates native or HTTP writer based on config

• Processor updates:

  • eap_items.rs - Refactored to remove #[serde(flatten)] (incompatible with Row derive)
  • Add clickhouse::Row derive to EAPItem struct

How to Enable

To use the native RowBinary client for a processor:

1. Add clickhouse::Row derive to the row struct
2. Change from InsertBatch::from_rows() to InsertBatch::from_rows_with_typed()
3. Set use_native_client: true in the storage's ClickHouse config

Test plan

• All 97 tests pass
• Build succeeds with no errors
• Type-aware merge tests verify batch accumulation works correctly

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