docs: add personal Claude Code notes for mirko

Personal, machine-syncable notes file (not referenced by any shared
AGENTS.md/CLAUDE.md, so it has no effect on other contributors).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GCaaQQSYGCbkAsRnALWC3h

AGENTS_mirko.md

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+# Personal notes — mirko
+
+Personal working notes for Claude Code sessions in this repo, for my own use across machines.
+Not project-wide guidance — nothing here applies to other contributors, and nothing else in
+this repo references or enforces it.
+
+## Repo ownership boundaries
+
+Root causes traced into BEC core (`bec_lib`/`bec_server`/`bec_ipython_client`, the `bec` repo)
+or into core `bec_widgets` are not mine to fix here — those are owned by their respective core
+teams. When an investigation in `csaxs_bec` turns up a bug whose fix belongs in one of those
+repos, write it up (a short report or plan) instead of implementing/committing it there.
+
+Fixes that land in `csaxs_bec` itself (beamline plugin code, widgets, device configs, scans)
+are mine to implement, commit, and push directly.