Fix columnMappings keys to dcid: predicate form (#102)

[tillywoodfield]

Closes #102.

What

ColumnMappings serialized its fields under short Python names (entity, variable, date, …), but the DCP importer keys observations by dcid:-prefixed predicate names. Any other key is treated as a custom dimension, so every exported config.json failed the import:

ValueError: Missing required column mapping for: 'dcid:variableMeasured'

How

Update ColumnMappings to accept either form on input and always emit the dcid: key on output.

field	emitted key
variable	dcid:variableMeasured
entity	dcid:observationAbout
date	dcid:observationDate
value	dcid:value
unit	dcid:unit
measurementMethod	dcid:measurementMethod
observationPeriod	dcid:observationPeriod
scalingFactor	scalingFactor (unchanged — see below)

scalingFactor

Left as the short scalingFactor key because the importer has no dcid:scalingFactor route yet.

Tests

• test_column_mappings_emit_dcid_keys — asserts the exact emitted key strings and that scalingFactor stays short (guards against alias typos).
• test_column_mappings_accepts_dcid_keys_on_input — read-back guard.
• Existing golden/round-trip tests pass against the updated fixture.

Co-authored with Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.35%. Comparing base (48aecf8) to head (130e1a1).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #117      +/-   ##
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+ Coverage   91.06%   93.35%   +2.29%     
==========================================
  Files          37       38       +1     
  Lines        1801     2048     +247     
==========================================
+ Hits         1640     1912     +272     
+ Misses        161      136      -25     

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[jm-rivera]

Thanks @tillywoodfield! it may be worth fixing a small linked issue. Since columnMappings is consumed by the importer, which requires the dcid prefixed keys, we need the serialisation to always work with the alias mapping.

To solve it, please just add by_alias=True to the model_dump call in config_to_dict(). You may have to update a related test that may not be expecting the dcid prefix on the keys.

[jm-rivera]

Thanks @tillywoodfield !