fix(presets): use dated Doubao model id and price 6-digit dated models

Volcengine Ark rejects the bare model name doubao-seed-2-1-pro with a 404
("model does not exist or you do not have access to it") even after the
model is activated; the API requires the full dated id
doubao-seed-2-1-pro-260628. Update the Doubao preset model id across all
apps (config default, generated catalog, and OpenClaw namespaced refs).

Pricing lookup only stripped 8-digit (YYYYMMDD) and ISO date suffixes, not
the 6-digit YYMMDD format Volcengine uses (-260628, -250615), so real
Doubao usage never matched the bare-name pricing seed and showed $0 cost.
Extend strip_model_date_suffix to also strip 6-digit YYMMDD (with
month/day validation to avoid eating non-date version suffixes), keeping
the bare-name pricing seed as the canonical identity. This also fixes
pricing for every other Volcengine Doubao model. Add unit and end-to-end
regression tests.

src/config/opencodeProviderPresets.ts

@@ -387,7 +387,7 @@ export const opencodeProviderPresets: OpenCodeProviderPreset[] = [
         setCacheKey: true,
       },
       models: {
-        "doubao-seed-2-1-pro": {
+        "doubao-seed-2-1-pro-260628": {
           name: "Doubao Seed 2.1 Pro",
         },
       },