fix: Auth.get fallback chain for profile keys

When looking up auth credentials:
- If profile key exists (e.g., 'minimax-coding-plan:personal'), use it
- If profile key doesn't exist but base provider does (e.g., 'minimax-coding-plan'), use that as fallback

This fixes the issue where build mode (no profile) wouldn't work when only 'minimax-coding-plan:personal' existed in auth.json.

Also removes normalizeKey usage from Auth.get - the fallback logic is now inline and clearer.

packages/opencode/src/auth/index.ts

@@ -71,19 +71,17 @@ export namespace Auth {
 
       const get = Effect.fn("Auth.get")(function* (providerID: string) {
         const allData = yield* all()
+        const bare = providerID.replace(/\/+$/, "")
         // Direct lookup (original behavior for backward compat with bare keys)
-        if (providerID in allData) return allData[providerID]
-        const withSlash = providerID.endsWith("/") ? providerID.slice(0, -1) : providerID + "/"
+        if (bare in allData) return allData[bare]
+        const withSlash = bare.endsWith("/") ? bare.slice(0, -1) : bare + "/"
         if (withSlash in allData) return allData[withSlash]
         // Multi-profile support: if key has embedded profile (provider:profile), try direct
         if (providerID.includes(":")) {
           if (providerID in allData) return allData[providerID]
+          // Profile specified but not found - try base provider without profile
+          if (bare in allData) return allData[bare]
         }
-        // Multi-profile support: try normalized key with :default
-        const withProfile = normalizeKey(providerID)
-        if (withProfile in allData) return allData[withProfile]
-        const bare = providerID.replace(/\/+$/, "")
-        if (`${bare}:default` in allData) return allData[`${bare}:default`]
         return undefined
       })