Merge PR #500: streaming support and security fixes

- feat(streaming): add streaming support for LLM responses (fixes #211)
- security(deps): remove vulnerable xmas-elf dependency via embuild (fixes #399)
- fix: resolve merge conflicts and integrate chat_with_tools from main

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

firmware/zeroclaw-esp32/Cargo.toml

@@ -22,7 +22,7 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 
 [build-dependencies]
-embuild = { version = "0.31", features = ["elf"] }
+embuild = "0.31"
 
 [profile.release]
 opt-level = "s"