fix(sbi/processor): trim inline comments per #61 review

@roundspring2003 asked across PRs for terse one-liner inline
comments and to move technical context to the commit message
and PR body. Drop the multi-line RFC/threat-model notes inline
and keep one-liners. Background:

* RFC 5448 §3 fixes the EAP-AKA' packet layout: 5-byte EAP
  header, 1-byte Subtype, 2 reserved bytes, then attribute TLVs
  starting at offset 3 of the post-header slice.
* A crafted NAS AuthenticationResponse carrying a 5-byte EAP
  payload (type field only) made eapPkt[5:] empty and data[0]
  panicked the AUSF (free5gc/free5gc#982).
* Each attribute is a 2-byte header (type, length/4) followed
  by value bytes. Without the truncated-header check, data[i+1]
  ran off the end on a payload missing the second header byte
  (free5gc/free5gc#983).

Signed-off-by: SAY-5 <SAY-5@users.noreply.github.com>

Author: SAY-5

internal/sbi/processor/ue_authentication.go

@@ -713,11 +713,7 @@ func decodeEapAkaPrime(eapPkt []byte) (*ausf_context.EapAkaPrimePkt, error) {
 	var attrLen int
 	var decodeAttr ausf_context.EapAkaPrimeAttribute
 	attributes := make(map[uint8]ausf_context.EapAkaPrimeAttribute)
-	// A well-formed EAP-AKA' packet has at least a 5-byte EAP header plus
-	// a 1-byte Subtype plus 2 reserved bytes (RFC 5448 §3) before the
-	// attribute TLVs begin at offset 3. A crafted NAS AuthenticationResponse
-	// carrying a 5-byte EAP payload (type field only) made eapPkt[5:] an
-	// empty slice and data[0] panicked (free5gc/free5gc#982).
+	// Bounds-check the EAP header before slicing.
 	if len(eapPkt) < 6 {
 		return nil, fmt.Errorf("EAP-AKA' packet too short: got %d bytes, need at least 6", len(eapPkt))
 	}
@@ -727,9 +723,7 @@ func decodeEapAkaPrime(eapPkt []byte) (*ausf_context.EapAkaPrimePkt, error) {
 
 	// decode attributes
 	for i := 3; i < dataLen; i += attrLen {
-		// Each attribute is a 2-byte header (type, length/4) followed by
-		// value bytes. Reject truncated headers instead of letting
-		// data[i+1] run off the end (free5gc/free5gc#983).
+		// Bounds-check the 2-byte attribute header.
 		if i+1 >= dataLen {
 			return nil, fmt.Errorf("EAP-AKA' attribute header truncated at offset %d", i)
 		}