lambda_functions_v10.0: Release v10.0 — security review pass + HA-driven interactive features

Built from improved branch. See README.md → 'What's different in this fork'
and TODO.md for the full delta vs upstream.

Highlights:
- All critical and high-severity security findings resolved (#1-#11)
- Echo Show defensive APL handling
- HA-driven interactive conversations (mid-session injection,
  cross-session memory via DynamoDB, auto-clear staged prompts)
- Updated docs: ARCHITECTURE.md, INTERACTIVE_HA.md, INSTALL/UPDATE

Built artifact: lambda_functions_v10.0.zip (4.38 MB, Linux x86_64,
Python 3.12 wheels). Attach to the GitHub Release for this tag for
distribution.