LEGACY protocol TVs fail with MQTT code 5 (static credentials required, not dynamic)

[duduroga]

Environment

• TV: Hisense OLED B5
• TV firmware: V0000.01.00L.L1021
• TV protocol version: 2150 (LEGACY)
• vidaa-control version: 1.1.0
• OS: Debian 13

Symptom

auth pair fails immediately with MQTT code 5 (not authorized) on LEGACY protocol TVs.

Root cause

In VidaaTV.__init__, when use_dynamic_auth=True and the protocol is detected as
LEGACY, the client generates dynamic LEGACY credentials. But LEGACY TVs require static
credentials (hisenseservice / multimqttservice). The _connect_with_fallback path
also only cycles through dynamic auth methods (MODERN, MIDDLE, LEGACY) and never tries
static credentials as a final fallback.

Fix

Two changes to client.py:

1. In __init__: when protocol detection returns LEGACY and no saved credentials exist,
   fall through to static credentials instead of generating dynamic LEGACY creds.

2. In _connect_with_fallback: after exhausting all dynamic auth methods, try static
   credentials as a final attempt.

With this fix applied, pairing and command sending work correctly:

• TV discovered as "Sala de estar", MAC e4:3b:c9:cb:16:b8, protocol 2150
• tv --ip 192.168.1.138 key HOME works

Workaround

Manually patch client.py in the installed package as described above.

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Additional finding: LEGACY protocol TVs (protocol version 2150) also do not support
PIN-based pairing. The config flow in ha-vidaa-tv unconditionally calls
async_start_pairing() and shows a PIN entry form, but LEGACY TVs ignore the pairing
request entirely and never display a PIN.

Fix: detect LEGACY protocol after async_connect() and skip the pairing step entirely —
create the config entry directly using the static credentials that were already
established during connection.

[bruno-rodrigues]

Please check the following request for a potential fix: #2