Add Orca — DeepSeek-native terminal coding agent

[echoVic]

What

Adds Orca to the Others section (README.md + README_cn.md), next to the existing terminal/CLI tools.

• Repo: https://github.com/echoVic/blade-deepseek
• Website: https://orcaagent.dev

Why it belongs here

Orca is a terminal coding agent built specifically for the DeepSeek API (not a generic multi-provider wrapper):

• Multi-turn agent loop with reasoning/content dual-stream SSE parsing, empty-turn recovery, and max reasoning effort by default
• Prefix-cache-friendly request construction: append-only conversation history and byte-stable tool schema serialization, so long agent sessions keep hitting DeepSeek's context cache; prompt_cache_hit_tokens is parsed and shown in the live cost display
• Automatic 1M-token context management with compaction at an 80% threshold
• Persistent goal mode, multi-stage workflow orchestration, subagents, and capability-based tool approval
• Single binary (Rust), installable via npm (@blade-ai/orca) or curl; macOS and Linux

Both English and Chinese README tables are updated with the same entry.