feat: always-on ELI16 + branch detection in preamble

- Add _BRANCH detection to preamble bash block (git branch --show-current)
- Merge ELI16 rules into default AskUserQuestion format (always-on)
- Remove _SESSIONS >= 3 conditional — better questions always
- Add simplification rules: plain English, no jargon, no raw function names
- Update tests for branch detection and simplification regression guard

test/skill-validation.test.ts

@@ -491,7 +491,7 @@ describe('v0.4.1 preamble features', () => {
     test(`${skill} contains session awareness`, () => {
       const content = fs.readFileSync(path.join(ROOT, skill), 'utf-8');
       expect(content).toContain('_SESSIONS');
-      expect(content).toContain('ELI16');
+      expect(content).toContain('RECOMMENDATION');
     });
   }
 });