Fix octopus_saving_session regex

[Meatballs1]

Missing parenthesis causing exceptions/crashes.

2026-03-31 10:07:58.831649: Error: Exception raised missing ), unterminated subpattern at position 1
2026-03-31 10:07:58.833245: Error: Traceback (most recent call last):
  File "/config/predbat.py", line 1565, in initialize
    self.auto_config()
  File "/config/userinterface.py", line 1077, in auto_config
    matched, arg_value = self.resolve_arg_re(arg, arg_value, state_keys)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/config/userinterface.py", line 1049, in resolve_arg_re
    res = re.search(my_re, key)
          ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/__init__.py", line 177, in search
    return _compile(pattern, flags).search(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/__init__.py", line 307, in _compile
    p = _compiler.compile(pattern, flags)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/_compiler.py", line 745, in compile
    p = _parser.parse(p, flags)
        ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/_parser.py", line 979, in parse
    p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/_parser.py", line 460, in _parse_sub
    itemsappend(_parse(source, state, verbose, nested + 1,
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/re/_parser.py", line 864, in _parse
    raise source.error("missing ), unterminated subpattern",
re.error: missing ), unterminated subpattern at position 1

Better fix would be to also catch the exception and print the offending line to the log.

[daviessm]

Can you do the same fix in all the inverter yamls? They were all broken as part of #3649

This will then fixes: #3713

[Meatballs1]

Thought it wouldn't be too tedious fixing them in the web interface but I was wrong :)

[daviessm]

Thought it wouldn't be too tedious fixing them in the web interface but I was wrong :)

Thanks! I started doing the same then pulled up the IDE and then saw your PR as I was about to start 😄