feat: support-evaluation-tracking-api

[Zaimwa9]

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Changes

Related JS client PR

Contributes to Flagsmith/flagsmith-openfeature-provider-python#34

Adds pipeline analytics support to the Python client, enabling buffered event tracking that posts to POST {url}v1/analytics/batch. This lays the groundwork for the OpenFeature provider to delegate its track() method to the client.

• PipelineAnalyticsConfig dataclass for configuration: analytics server URL, buffer size, and flush interval
• PipelineAnalyticsProcessor event processor with:
  • record_evaluation_event(), automatic on get_flag() call, deduplicated within each flush window
  • record_custom_event(), explicit, never deduplicated
  • Periodic flush
  • Failed flush re-queues events (capped at max_buffer)
• Flagsmith.track_event() — public API for recording custom events
• Flags.get_flag(), automatically records evaluation events when a pipeline processor is configured
• resolve_trait_values() — extracted shared helper for unwrapping TraitConfig

How did you test this code?

• Added tests