Add get_mode_settings(), set_mode_reserve(); fix get_mode()Add tou reserve methods

[npdsomerhayes]

Summary

Fixes the long-standing broken get_mode() and adds two new methods built
on a previously undocumented API endpoint discovered via MITM interception
of the FranklinWH mobile app.

get_mode() had a TODO comment acknowledging it was wrong:

• runingMode from _switch_status() is not a stable mode identifier —
  it appears to be a rolling/schedule ID that changes between polls even
  when the mode hasn't changed
• touMinSoc / selfMinSoc / backupMaxSoc do not reflect the
  user-visible battery reserve percentage
• The result was that get_mode() raised KeyError

New endpoint: getGatewayTouListV2

POST /hes-gateway/terminal/tou/getGatewayTouListV2?showType=1

Returns all three operating modes with their reserve SOC percentages and
identifies the currently active mode via currendId (sic — API typo):

{
  "result": {
    "currendId": 83132,
    "list": [
      {"id": 83132, "workMode": 1, "name": "Free power",        "soc": 10.0, "editSocFlag": true},
      {"id": 79680, "workMode": 2, "name": "Self-Consumption",  "soc": 10.0, "editSocFlag": true},
      {"id": 77244, "workMode": 3, "name": "Emergency Backup",  "soc": 100.0,"editSocFlag": false}
    ]
  }
}

workMode 1/2/3 uses the same encoding as Mode.workMode. The id values
are installation-specific and differ from the hardcoded values in the Mode
factory methods (9322/9323/9324), which are correct for updateTouMode and
unrelated to these schedule-entry IDs.

New endpoint: updateSocV2

POST /hes-gateway/terminal/tou/updateSocV2?workMode=2&electricityType=1&soc=15

Updates the reserve SOC for a single mode without switching to that mode.
electricityType=1 is always required (purpose unknown, discovered via MITM).
Emergency Backup always has editSocFlag: false; the server rejects writes.

Changes

New: get_mode_settings() -> ModeSettings

Returns a ModeSettings dataclass (consistent with the existing
ExportSettings pattern) containing all mode configurations and the active
mode. Convenience properties: .current_work_mode and .reserves.

New: set_mode_reserve(work_mode, soc)

Updates one mode's reserve without switching modes. Validates inputs before
the API call and raises InvalidDataException on API failure.

Fixed: get_mode()

Rewritten to use get_mode_settings(). Preserves the existing
(mode_name, soc) return signature. Now raises InvalidDataException
(consistent with the rest of the library) instead of KeyError.

New: WORK_MODE_MAP, ModeInfo, ModeSettings exported from __init__

Tested

bin/test-tou-reserve.py (included) exercises all three methods against a
real gateway. Confirmed working.

── get_mode_settings() ─────────────────────────────────────────
  current_mode_id  : 83132
  current_work_mode: 1 (time_of_use)
  reserves         : {1: 10.0, 2: 10.0, 3: 100.0}
  modes:
    workMode=1  id= 83132  soc= 10.0%  editable   name='Free power' (user-defined tariff label) ← active
    workMode=2  id= 79680  soc= 10.0%  editable   name='Self-Consumption'
    workMode=3  id= 77244  soc=100.0%  read-only  name='Emergency Backup'

Note: name is the user's custom tariff profile label as set in the FranklinWH app — it is not a fixed mode identifier. The example above shows "Free power" which is the name of this user's electricity plan. Use workMode (1/2/3) to identify the mode type reliably.

get_mode()
  mode_name: 'time_of_use'
  soc      : 10.0%

── set_mode_reserve(work_mode=1, soc=10) [time_of_use, no-op] 
 Success — value written back unchanged
 Confirmed reserve still 10.0%

── All tests passed ────────────────────────────────────────────