refactor: remove legacy tools format, use permission only

BREAKING: Requires OpenCode 1.1.1+

- Remove supportsNewPermissionSystem/usesLegacyToolsSystem checks
- Simplify permission-compat.ts to permission format only
- Unify explore/librarian deny lists: write, edit, task, sisyphus_task, call_omo_agent
- Add sisyphus_task to oracle deny list
- Update agent-tool-restrictions.ts with correct per-agent restrictions
- Clean config-handler.ts conditional version checks
- Update tests for simplified API

src/shared/opencode-version.ts

@@ -1,6 +1,10 @@
 import { execSync } from "child_process"
 
-export const PERMISSION_BREAKING_VERSION = "1.1.1"
+/**
+ * Minimum OpenCode version required for this plugin.
+ * This plugin only supports OpenCode 1.1.1+ which uses the permission system.
+ */
+export const MINIMUM_OPENCODE_VERSION = "1.1.1"
 
 const NOT_CACHED = Symbol("NOT_CACHED")
 let cachedVersion: string | null | typeof NOT_CACHED = NOT_CACHED
@@ -53,14 +57,10 @@ export function getOpenCodeVersion(): string | null {
   }
 }
 
-export function supportsNewPermissionSystem(): boolean {
-  const version = getOpenCodeVersion()
-  if (!version) return true
-  return isVersionGte(version, PERMISSION_BREAKING_VERSION)
-}
-
-export function usesLegacyToolsSystem(): boolean {
-  return !supportsNewPermissionSystem()
+export function isOpenCodeVersionAtLeast(version: string): boolean {
+  const current = getOpenCodeVersion()
+  if (!current) return true
+  return isVersionGte(current, version)
 }
 
 export function resetVersionCache(): void {