Climate: show antifreeze (102) and thermal protection (202) of the central unit instead of both as off #699

Split out of #697 (second comment by @ricdijk). Not a bug in the frames, a gap in what Home Assistant shows.

What is the problem

On a 99-zone central unit (WHERE #0) the integration shows two different central states as the same HVAC mode, off:

Reported plant: F454, firmware 1.0.34, MyHOME 2.0.0b15. Switching the season switch on the central control panel to "Estate" then "Inverno" gave:

20:07:11  *4*202*#0##   -> Zone 0's mode is set to 'off'   (zones then follow with *4*202*Z## and *#4*Z*12*0350*3##)
20:07:19  *4*102*#0##   -> Zone 0's mode is set to 'off'   (zones then follow with *4*102*Z## and *#4*Z*12*0070*3##)

After the switch to Inverno no 110#… frame followed, so the entity stayed off with no setpoint although the central was in antifreeze at 7 °C. For people who only see the central as on/off this hides the state.

Traces: #697 comment 6129809756 (F454) and the F453AV captures in OWNd#97. Both plants pair 202 with the summer side and 102 with the winter side. One switch in each direction was seen on the F454, so "always" is not confirmed.

Proposal

1. Keep the HVAC mode off.
2. Expose the central's season (heating / conditioning) as a state attribute. This needs no new write path; zones already have a season attribute (*4*1*Z## → hvac_season).
3. Add antifreeze / thermal_protection presets only if a plant shows a central in protection without a season change.
4. Docs note: the central only reports a setpoint (*4*110#0170*#0##) after one was set natively; the dimension-14 query *#4*#0*14## is rejected (Central unit (WHERE #0) is marked "unresponsive" after two restarts, although it answers a plain status request #629 / fix(climate): poll 99-zone central unit with plain status request (#629) #636).

Depends on OpenWebNet-HA/OWNd#97 being merged and released (it ships together with #657).

Open questions

• Does the panel's season switch always leave the central in its off state for that season, or must another mode be chosen afterwards?
• Does a central in other states always omit the setpoint?
• Does a 3550 / 4695 answer the same way as the F454 and F453AV?

Traces of the central in these states (season switch, off, antifreeze, thermal protection, back to a program) from other 99-zone or 4-zone plants would settle the questions.