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/dispatch.ts

@@ -26,7 +26,7 @@ export type DispatchOpts = {
   issueDescription: string;
   issueUrl: string;
   role: "dev" | "qa" | "architect";
-  /** Developer level (junior, medior, senior, reviewer, opus, sonnet) or raw model ID */
+  /** Developer level (junior, mid, senior) or raw model ID */
   level: string;
   /** Label to transition FROM (e.g. "To Do", "To Test", "To Improve") */
   fromLabel: string;