Improve entity definitions: Heat Type select, 60 Min Timer switch, Delay Timer label

[irk645]

Tested and validated on a Finnleo SaunaLogic2 (TyloHelo SL2) in May 2026.

Changes:

• DP 4 (Heat Type): converted from read-only sensor to select entity. Confirmed writable directly from tuya_local. Values: IR (Infrared), TRAD (Traditional), NONE.
• DP 9 (60 Min Timer): converted from diagnostic integer sensor to switch entity. Confirmed bidirectional control from HASS. 0 = no timer, 1 = 60 min auto-shutoff.
• DP 105 (Delay Timer): renamed from 'Sauna state' for clarity, added unit: h. Note: delay only activates when set after the heater is turned on. The countdown is visible in the Tuya app but does not appear to be exposed as a separate readable DP.