fix: thread dialect through altimate_core.policy handler

Code review (Gemini 3.1 Pro) caught a missed handler in the
dialect-threading migration: 'altimate_core.policy' (altimate-core.ts:200)
called schemaOrEmpty() without params.dialect, while the 6 other policy-
family handlers (validate, check, fix, semantics, equivalence, correct,
explain) all pass it through.

AltimateCorePolicyParams already declares 'dialect?: string' in types.ts
and the tool definition plumbs it into Dispatcher.call(), so the param
was reaching the handler but being silently discarded at the schema
resolution step — meaning the fallback empty schema was always built
with the default (Snowflake) dialect instead of the user-selected one,
defeating the purpose of PR #550 for policy checks specifically.

1-line fix brings the policy handler into line with its 6 siblings.

Author: VJ-yadav

packages/opencode/src/altimate/native/altimate-core.ts

@@ -197,7 +197,7 @@ export function registerAll(): void {
   // 8. altimate_core.policy
   register("altimate_core.policy", async (params) => {
     try {
-      const schema = schemaOrEmpty(params.schema_path, params.schema_context)
+      const schema = schemaOrEmpty(params.schema_path, params.schema_context, params.dialect)
       const raw = await core.checkPolicy(params.sql, schema, params.policy_json)
       const data = toData(raw)
       return ok(true, data)