🐛 fix: resolve port conflicts and state pollution in test validation

- Remove FIXED_TEST_PORT and BDD_SCHEMA_ISOLATION from validate-test-suite.sh
- Change go test ./features/... to go test ./features to avoid duplicate runs
- Update recommendations to prioritize investigation over flaky tagging
- Remove @flaky tags now that root causes are fixed

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

features/jwt/jwt_secret_rotation.feature

@@ -11,7 +11,6 @@ Feature: JWT Secret Rotation
     Then the authentication should be successful
     And I should receive a valid JWT token signed with the primary secret
 
-  @flaky
   Scenario: Token validation with multiple valid secrets
     Given the server is running with multiple JWT secrets
     And a user "tokenuser" exists with password "testpass123"
@@ -22,7 +21,6 @@ Feature: JWT Secret Rotation
     Then the token should be valid
     And it should contain the correct user ID
 
-  @flaky
   Scenario: Secret rotation - adding new secret while keeping old one valid
     Given the server is running with primary JWT secret
     And a user "rotateuser" exists with password "testpass123"
@@ -42,7 +40,6 @@ Feature: JWT Secret Rotation
     Then the authentication should fail
     And the response should contain error "invalid_token"
 
-  @flaky
   Scenario: Graceful secret rotation with user continuity
     Given the server is running with primary JWT secret
     And a user "gracefuluser" exists with password "testpass123"