feat(environment): introduce disable_omo_env configuration option

- Added a new configuration option `disable_omo_env` to control the injection of the `<omo-env>` block in agent prompts.
- Updated relevant functions and tests to support this feature, ensuring that the environment context can be toggled on or off as needed.
- Enhanced documentation to reflect the new option and its implications for API cost and cache hit rates.

src/agents/builtin-agents/sisyphus-agent.ts

@@ -22,6 +22,7 @@ export function maybeCreateSisyphusConfig(input: {
   directory?: string
   userCategories?: CategoriesConfig
   useTaskSystem: boolean
+  disableOmoEnv?: boolean
 }): AgentConfig | undefined {
   const {
     disabledAgents,
@@ -36,6 +37,7 @@ export function maybeCreateSisyphusConfig(input: {
     mergedCategories,
     directory,
     useTaskSystem,
+    disableOmoEnv = false,
   } = input
 
   const sisyphusOverride = agentOverrides["sisyphus"]
@@ -78,7 +80,9 @@ export function maybeCreateSisyphusConfig(input: {
   }
 
   sisyphusConfig = applyOverrides(sisyphusConfig, sisyphusOverride, mergedCategories, directory)
-  sisyphusConfig = applyEnvironmentContext(sisyphusConfig, directory)
+  sisyphusConfig = applyEnvironmentContext(sisyphusConfig, directory, {
+    disableOmoEnv,
+  })
 
   return sisyphusConfig
 }