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.lock

@@ -483,7 +483,6 @@ dependencies = [
  "tempfile",
  "thiserror 1.0.69",
  "which",
- "xmas-elf",
 ]
 
 [[package]]
@@ -1806,21 +1805,6 @@ dependencies = [
  "wasmparser",
 ]
 
-[[package]]
-name = "xmas-elf"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42c49817e78342f7f30a181573d82ff55b88a35f86ccaf07fc64b3008f56d1c6"
-dependencies = [
- "zero",
-]
-
-[[package]]
-name = "zero"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2fe21bcc34ca7fe6dd56cc2cb1261ea59d6b93620215aefb5ea6032265527784"
-
 [[package]]
 name = "zeroclaw-esp32"
 version = "0.1.0"