fix(tests): update snapshots and positional arg indices for athena/council-member params

- Regenerate model-fallback snapshots to include athena agent config
- Fix createBuiltinAgents positional arg index for disableOmoEnv
  (shifted from index 12 to 13 by new councilConfig param)
- Fix utils.test.ts, config-handler.test.ts arg positions

src/agents/utils.test.ts

@@ -807,6 +807,7 @@ describe("Hephaestus environment context toggle", () => {
       undefined,
       undefined,
       undefined,
+      undefined,
       disableFlag
     )
   }
@@ -866,6 +867,7 @@ describe("Sisyphus and Librarian environment context toggle", () => {
       undefined,
       undefined,
       undefined,
+      undefined,
       disableFlag
     )
   }
@@ -925,6 +927,7 @@ describe("Atlas is unaffected by environment context toggle", () => {
       undefined,
       undefined,
       undefined,
+      undefined,
       false
     )
 
@@ -941,6 +944,7 @@ describe("Atlas is unaffected by environment context toggle", () => {
       undefined,
       undefined,
       undefined,
+      undefined,
       true
     )