chore(release): 0.2.6

[ShortArrow]

Release 0.2.6. Bumps Directory.Build.props <Version> and adds the CHANGELOG entry. After merge, push the annotated tag v0.2.6 to trigger release.yml.

Consolidates three merged feature PRs:

• fix(vxi11): resolve Core port via TCP/111 portmapper GETPORT (#20) #55 fix(vxi11) — real UDP/111 portmapper GETPORT with fixed-port fallback (closes VXI-11 client backend: real portmapper (UDP/111) round-trip #20)
• fix(scan): probe every NIC's subnet broadcast for VXI-11 discovery #60 fix(scan) — per-NIC subnet-directed broadcast + unmasked scan output
• feat(cli): show resource string in visa list (human + json) #61 feat(cli) — visa list shows the canonical resource string

See CHANGELOG [0.2.6] for details, including the Kikusui PWR801L field notes.

Post-merge

git checkout main && git pull
git tag -a v0.2.6 -m "v0.2.6 — VXI-11 portmapper, multi-NIC scan, visa list resource"
git push --follow-tags