refactor: standardize level names across all roles (#195 phase 1)

Rename levels to use consistent industry-standard terminology:
- dev: medior → mid
- qa: reviewer → mid, tester → junior, add senior level
- architect: opus → senior, sonnet → junior

Add backward-compatible migration for projects.json and openclaw.json
config via level aliases in selectors and projects parser.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/tools/autoconfigure-models.ts

@@ -102,7 +102,7 @@ export function createAutoConfigureModelsTool(api: OpenClawPluginApi) {
         if (modelCount === 1) {
           message += "ℹ️  Only one authenticated model found — assigned to all roles.";
         } else {
-          message += "ℹ️  Models assigned by capability tier (Tier 1 → senior, Tier 2 → medior/reviewer, Tier 3 → junior/tester).";
+          message += "ℹ️  Models assigned by capability tier (Tier 1 → senior, Tier 2 → mid, Tier 3 → junior).";
         }
 
         if (preferProvider) {