1.2.1 - energiedaten.at readings + Netz NOE login fixed

Bug-fix release for the two open issue reports.

Requirements: Home Assistant 2026.9 or newer.

🔧 Fixed

energiedaten.at returned no readings (issue #6)

The adapter sent an obis_codes[] filter that the documented data endpoint does not
have, and asked for one hard-coded day per poll. A poll that landed before the grid
operator delivered therefore answered with an empty window — and that day was never read
again, because the coordinator had already moved on to the next one.

A poll now reads the last seven days in one request (from, to and the order
parameter the platform's own Home Assistant integration sends), follows the
is_truncated/next_cursor pagination of the server's record cap, selects the OBIS codes
client-side and reports the newest day that actually carries readings. The meter-wide
total (G.01) is preferred over the grid figure (P.01) — as the platform's own analyses
do — instead of the other way round, and the two are never added up.

Each reading now carries the day it belongs to (day, period_from, period_to) and the
code it was read from (source_obis_code). A "no data" log line names the whole window
that was read.

The Netz Niederösterreich setup (issue #5)

The portal answers POST /orchestration/Authentication/Login with HTTP 200 and an empty
body while it sets the session cookie. Requiring JSON of that body made every setup
attempt fail with

… returned a non-JSON response (HTTP 200): ''

although the credentials were accepted. HTTP 200 is now the success it is; only a non-200
status, a 401/403 or an explicit {"success": false} is a failed login.

• An unauthenticated data call is reported as a credentials problem instead of a
  connection problem, so the config flow shows invalid authentication where it used to
  show could not connect.
• The metering point endpoints are asked with context=2, the context both independent
  third-party clients of this portal use (5 was not).
• A meter that is in an energy community no longer has its own record and its community
  records summed up together, which counted the same energy twice.

🎨 Brand images

The integration's brand images are built from the project banner
(austria_smartmeter.jpg): the icon is a square around the smart meter with the Austrian
flag, the logo a 4:1 band through the banner. dark_logo is identical to logo, because
the banner is dark.

📝 Documentation

• New CHANGELOG.md with the full history from 1.1.6 on.
• Reworked README with the project banner, a table of contents, per-provider setup
  notes, troubleshooting entries for both reported issues and a roadmap.

Full changelog: see CHANGELOG.md.

---

Both fixes follow the documented contracts, but neither could be verified against a live
account of ours — energiedaten.at needs a consent-connected metering point, Netz
Niederösterreich a portal account. If a sensor still stays empty, the debug log (and the
diagnostics download) now names what was asked and what came back, so please keep
reporting.