fix(app): keep orGUI operational when the database drive disconnects

[tifuchs]

fixes database disconnect error path described in issue #23
by subclassing Hdf5TreeModel and overwriting
_closeFileIfOwned
that caused the crash.

[tifuchs]

Note: master history was rewritten on 2026-08-11.

A Co-Authored-By trailer was removed from 7459b38 ("docs: add CLAUDE.md
and close AGENTS.md coverage gaps"). Removing it required rewriting that
commit and every commit that followed it on master, so this PR's merge
commit has a new SHA:

	commit
before	bb0a154
after	674d1b2

Only commit messages changed. Every rewritten commit keeps an identical tree,
author and committer, and all merges remain merges, so the code on master is
byte-for-byte what it was.

This PR itself is unaffected: it stays merged, and its commits and diff (served
from refs/pull/67/head) still resolve. Only the "merged commit bb0a154 into
master" reference above now points at a commit that is no longer reachable from
master.