docs: list feature-gated models

[peter941221]

The README supported-models table drifted behind the server's actual model detection logic.

Failure mechanism:

• pegainfer-server/src/server_engine.rs already exposes feature-gated DeepSeekV2Lite and KimiK2 model lines
• the top-level README only listed Qwen3, Qwen3.5, and DeepSeek-V4-Flash
• readers could miss that the server can also detect DeepSeek-V2-Lite and Kimi-K2 configs when built with the matching feature flags

Semantic change:

• add DeepSeek-V2-Lite and Kimi-K2 to the README supported-models table
• clarify that feature-gated model lines require rebuilding pegainfer-server with the matching --features ... flag before launch

Testing:

• source verification against pegainfer-server/src/server_engine.rs:10-18, :44-58, and :75-92

[gemini-code-assist]

Code Review

This pull request updates the README.md file to document support for DeepSeek-V2-Lite and Kimi-K2 models. Feedback was provided regarding an inconsistency in the supported models table, where the string "feature-gated" was incorrectly placed in the Params column instead of the Status column. A suggestion was provided to align these rows with the correct table structure and include the actual parameter counts.