feat(mcp): check_env struct-level granularity via composes selectors

Patch to v1.1.1. check_env could only reason at module granularity, so a var
that lives on one struct of a multi-struct module (e.g. EINHERJAR_SERVER_CORS_ORIGINS
on web.Config, not web/server.Config) couldn't be flagged dead when the app
composes the sibling struct. Adds struct-level selectors to close that gap.

internal/tools (check_env):
- New `composes` input: exact config structs as module/subpackage/Struct selectors
  (e.g. web/server/Config, db-postgres/Config, core/logz/Config), alongside or
  instead of the coarse `modules` list.
- not-composed now reasons over the union of composed vars (from modules AND
  struct selectors), so it surfaces struct-level dead vars. Coarse modules:["web"]
  keeps the prior behavior.
- parseStructSelector helper; errors on malformed or non-existent selectors.

Tests: struct-level dead-var catch (CORS flagged with web/server/Config but not
with module web), bad-selector errors; existing calls updated to the new arg.
Version bumped to v1.1.1 (badge + serverVersion). No dependency changes.

cmd/server/main.go

@@ -23,7 +23,7 @@ import (
 
 const (
 	serverName    = "einherjar-mcp"
-	serverVersion = "v1.1.0"
+	serverVersion = "v1.1.1"
 )
 
 func main() {