Update debian:13-slim Docker digest to b6e2a15

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
debian	final	digest	109e2c6 → b6e2a15

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🤖 Claude Code Review

Code Review

This is a base image digest bump (debian:13-slim) — a routine dependency update.

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Code Quality

	Item	Notes
✅	Code style	Single-line change, no style issues
✅	No commented-out code	N/A
✅	Meaningful variable names	BASE_IMAGE is clear
✅	DRY principle	N/A
✅	Defects / bugs	No logic errors introduced
❌	REFRESHED_AT not updated	Dockerfile:11 shows REFRESHED_AT=2026-05-21, but today is 2026-05-31. Per CLAUDE.md, updating the base image digest requires also updating REFRESHED_AT to the current date. The verify-dockerfile-refreshed-at-updated.yaml CI workflow will fail if these are out of sync.
✅	CLAUDE.md is appropriate	General guidance, not environment-specific

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Testing

	Item	Notes
✅	Tests	Existing docker-test verifies installed files; no new logic to unit test

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Documentation

	Item	Notes
✅	README / API docs	No functional change requiring doc updates
✅	CHANGELOG	Dependency-only digest bump; no changelog entry expected

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Security

	Item	Notes
✅	No hardcoded credentials	Clean
✅	Input validation	N/A
✅	No license files	No .lic / AQAAAD strings

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Summary

One blocking issue: REFRESHED_AT on Dockerfile:11 must be updated from 2026-05-21 to 2026-05-31 (today's date) to satisfy the verify-dockerfile-refreshed-at-updated.yaml workflow requirement documented in CLAUDE.md.

Automated code review analyzing defects and coding standards