chore: apply release 0.4 delta to main

[Yunnglin]

Summary

Apply the final release/0.4 delta on top of current main.

This keeps main's agentic training changes while carrying over the release-specific updates that are still different from main:

• set package/version metadata to 0.4.0
• pin tinker to 0.16.1
• pin Docker Redis and Grafana LGTM image versions
• use python -m pip in Docker install steps and print Python/pip versions before installing runtime deps

Validation

• git diff --check

[gemini-code-assist]

Code Review

This pull request prepares the project for the 0.4.0 release by updating version numbers, pinning base image tags (Redis and Otel-LGTM) in the Dockerfile, and upgrading the tinker dependency to version 0.16.1. Additionally, the Dockerfile is updated to use python -m pip instead of pip. Feedback was provided to include the --no-cache-dir flag when installing the local package in the Dockerfile to minimize the final image size.

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