feat(plugins): update plugin format to new entry_point + [[providers]] style

- owlry-core/manifest: add entry_point alias for entry field, add ProviderSpec
  struct for [[providers]] array, change default entry to main.lua
- owlry-lua/manifest: add ProviderDecl struct and providers: Vec<ProviderDecl>
  for [[providers]] support
- owlry-lua/loader: fall back to manifest [[providers]] when script has no API
  registrations; fall back to global refresh() for manifest-declared providers
- owlry-lua/api: expose call_global_refresh() that calls the top-level Lua
  refresh() function directly
- owlry/plugin_commands: update create templates to emit new format:
  entry_point instead of entry, [[providers]] instead of [provides],
  main.rn/main.lua instead of init.rn/init.lua, Rune uses Item::new() builder
  pattern, Lua uses standalone refresh() function
- cmd_validate: accept [[providers]] declarations as a valid provides source

crates/owlry-lua/src/api/mod.rs

@@ -50,3 +50,8 @@ pub fn call_refresh(lua: &Lua, provider_name: &str) -> LuaResult<Vec<PluginItem>
 pub fn call_query(lua: &Lua, provider_name: &str, query: &str) -> LuaResult<Vec<PluginItem>> {
     provider::call_query(lua, provider_name, query)
 }
+
+/// Call the global `refresh()` function (for manifest-declared providers)
+pub fn call_global_refresh(lua: &Lua) -> LuaResult<Vec<PluginItem>> {
+    provider::call_global_refresh(lua)
+}