* fix(#1581): config-set no longer silently coerces Infinity/project_code
The value parser used !isNaN(Number(val)), which admits Infinity/-Infinity;
JSON.stringify then renders those as null on disk while the CLI echoed the
non-finite value (output ≠ disk). Leading-zero strings like project_code
'007' were also silently number-coerced to 7.
- config.cts parser: Number.isFinite instead of !isNaN, so Infinity falls
through to the JSON branch (rejected) and stays a string.
- project_code: always persisted as a string (identifier; leading zeros
matter), bypassing number coercion.
- context_window: new per-key validator — must be a finite positive integer
(rejects Infinity/0/negatives/non-integers with a non-zero exit).
- tests/config.test.cjs: #1581 regression (Infinity rejected, 0 rejected,
200000 accepted finite, project_code '007' string-preserved, granularity
numeric coercion unchanged).
Closes#1581
* docs(#1581): backfill changeset pr 2023
