fix: address Copilot review comments

- Add legacy '// +build' directives for backward compatibility
- Fix CheckOrigin to actually validate same-origin requests
- Add strings import for origin checking

Author: leifj

bootstrapping/eduid.json

@@ -1,4 +1,5 @@
 //go:build didcomm && vc20
+// +build didcomm,vc20
 
 // Package crypto provides HSM and external signer support for DIDComm operations.
 package crypto

bootstrapping/ehic.json

@@ -1,4 +1,5 @@
 //go:build didcomm && vc20
+// +build didcomm,vc20
 
 package issuecredential
 

bootstrapping/pda1.json

@@ -1,4 +1,5 @@
 //go:build didcomm && vc20
+// +build didcomm,vc20
 
 // Package issuecredential implements the DIDComm Issue Credential protocol 3.0.
 //

bootstrapping/pid-1-5.json

@@ -1,4 +1,5 @@
 //go:build didcomm && vc20
+// +build didcomm,vc20
 
 package presentproof
 

bootstrapping/pid-1-8.json

@@ -1,4 +1,5 @@
 //go:build didcomm && vc20
+// +build didcomm,vc20
 
 // Package presentproof implements the DIDComm present-proof protocol 3.0.
 // This protocol enables requesting and presenting verifiable credentials