Asset parser can't determine realm for MOM5 regional outputs

[aekiss]

Describe the bug

Can't determine realm for MOM5 "regional" outputs (i.e. outputs from spatially restricted subsets from global model run, not regional model).

To Reproduce

import intake 
from access_nri_intake.source.builders import AccessOm2Builder, AccessOm3Builder

builder = AccessOm3Builder(
    path="/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine"
).build()

yields

---------------------------------------------------------------------------
ParserError                               Traceback (most recent call last)
Cell In[1], line 6
      1 import intake 
      2 from access_nri_intake.source.builders import AccessOm2Builder, AccessOm3Builder
      4 builder = AccessOm3Builder(
      5     path="[/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine](https://are.nci.org.au/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine)"
----> 6 ).build()

File [/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py:203](https://are.nci.org.au/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py#line=202), in BaseBuilder.build(self)
    198 def build(self):
    199     """
    200     Builds a datastore from a list of netCDF files or zarr stores.
    201     """
--> 203     self.get_assets().validate_parser().parse().clean_dataframe()
    205     return self

File [/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py:191](https://are.nci.org.au/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py#line=190), in BaseBuilder.validate_parser(self)
    188         validate_against_schema(info, ESM_JSONSCHEMA)
    189         return self
--> 191 raise ParserError(
    192     f"""Parser returns no valid assets.
    193     Try parsing a single file with Builder.parser(file)
    194     Last failed asset: {asset}
    195     Asset parser return: {info}"""
    196 )

ParserError: Parser returns no valid assets.
            Try parsing a single file with Builder.parser(file)
            Last failed asset: [/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc](https://are.nci.org.au/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc)
            Asset parser return: {'INVALID_ASSET': '[/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc](https://are.nci.org.au/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc)', 'TRACEBACK': 'Traceback (most recent call last):\n  File "[/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py", line 514](https://are.nci.org.au/g/data/xp65/public/apps/med_conda/envs/analysis3-25.09/lib/python3.11/site-packages/access_nri_intake/source/builders.py#line=513), in parser\n    raise ParserError(f"Cannot determine realm for file {file}")\naccess_nri_intake.source.builders.ParserError: Cannot determine realm for file [/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc](https://are.nci.org.au/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc)\n'}

An example offending file is
/g/data/ik11/outputs/access-om2-01/01deg_jra55v13_ryf9091_DSW_BasalGade_NoIcb_Brine/output088/ocean/rregionocean_daily_3d_vhrho_nt.nc

Additional context

We occasionally use MOM5's regional outputs feature to save space.

[charles-turner-1]

Is it straightforward for you to include the realm as a metadata field within the file? We've updated the builders to default to that where possible - it would be the easiest fix.