Replace PlatformId's per-method match arms with static PlatformSpec rows
read through a single spec() accessor. Zero behavior change (adversarially
reviewed: ids, display names, base URLs + env override pairing, oauth flag,
prefix filters, and api-key env precedence order are byte-identical; all
public signatures unchanged). Groundwork for the multi-provider expansion:
adding a platform becomes variant + ALL entry + spec() arm + row.
Guards added for the row-addition workflow: spec-id uniqueness test (parse
scans rows) and a compile-forced ALL-completeness test (a variant missing
from ALL would otherwise be silently unparseable and skipped by model
sync). Future-proofed two assertions that hardcoded 'openai' as an
unknown-platform example.
ZacharyZhang-NY
99d99fb47a