v0.1.0

Make the license machine-detectable, add HACS badges to the README

HACS's license check failed with "SPDX: NOASSERTION". The cause was the
attribution paragraph appended below the MIT text in LICENSE: GitHub's
licensee only reports a license when the file matches a known license
body, and trailing prose defeats that match, so the repository looked
unlicensed to every tool that asks GitHub instead of reading the file.

LICENSE is now the bare MIT text, byte-identical to the canonical form.
Nothing is given up by that - the upstream 0xAHA/Growatt_ModbusTCP notice
that paragraph pointed at was never in LICENSE itself, only referenced
from it, and it still sits in NOTICE.md section 1 in full, which is what
that project's license actually requires. NOTICE.md now says why LICENSE
has to stay bare, so the paragraph does not get helpfully added back.

Also adds the badge row the main README was missing: HACS custom
repository, latest release, minimum Home Assistant version (matching
hacs.json), MIT, and the Validate workflow status.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182STGQ6RbSjMFZbVhSYQ1L