`platforms.webhook.port: 9100` (and `routes`, `secret`, api_server `key`/
`cors_origins`, any adapter setting) was silently dropped unless nested
under `extra:` — PlatformConfig.from_dict only read a fixed set of typed
fields. Two partial bridges (a per-platform port/host/secret table in the
loader and an api_server-only block) covered a few keys and had to be
extended for every new one.
from_dict now promotes every non-typed top-level key into `extra`, with an
explicit `extra:` value winning on a clash and typed fields never leaking
into `extra` on a to_dict/from_dict roundtrip. Both hand-written bridges
are removed.
Same direction as PRs #10208/#10211/#10453 (rainow's #10206 diagnosis) and
#20506; those targeted the pre-loader layout.
Fixes#10206
teknium1
2f3ccfa3bd