fix: post-then-cleanup flow, remove dead code, pagination

- PostReview now returns *Review (id + user login from response)
- Delete flow: post first, then delete stale reviews by same user
- No read:user scope needed (identity from POST response)
- Removed GetAuthenticatedUser (requires scope we lack)
- ListReviews: full pagination (loops until partial page)
- envOrDefaultBool: case-insensitive, whitespace-trimmed
- action.yml: document accepted boolean values
- Tests updated for new PostReview signature

cmd/review-bot/main.go

@@ -196,34 +196,30 @@ func main() {
 		return
 	}
 
-	// Delete previous reviews from this bot if update-existing is enabled
-	if *updateExisting {
-		login, err := giteaClient.GetAuthenticatedUser(ctx)
+	log.Printf("Posting review (event=%s)...", event)
+	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, event, reviewBody)
+	if err != nil {
+		log.Fatalf("Failed to post review: %v", err)
+	}
+	log.Printf("Review posted (id=%d, user=%s)", posted.ID, posted.User.Login)
+
+	// Delete stale reviews from this bot if update-existing is enabled
+	if *updateExisting && posted.User.Login != "" {
+		reviews, err := giteaClient.ListReviews(ctx, owner, repoName, prNumber)
 		if err != nil {
-			log.Printf("Warning: could not determine reviewer identity: %v", err)
+			log.Printf("Warning: could not list existing reviews: %v", err)
 		} else {
-			reviews, err := giteaClient.ListReviews(ctx, owner, repoName, prNumber)
-			if err != nil {
-				log.Printf("Warning: could not list existing reviews: %v", err)
-			} else {
-				for _, r := range reviews {
-					if r.User.Login == login {
-						if err := giteaClient.DeleteReview(ctx, owner, repoName, prNumber, r.ID); err != nil {
-							log.Printf("Warning: could not delete old review %d: %v", r.ID, err)
-						} else {
-							log.Printf("Deleted previous review %d", r.ID)
-						}
+			for _, r := range reviews {
+				if r.User.Login == posted.User.Login && r.ID != posted.ID {
+					if err := giteaClient.DeleteReview(ctx, owner, repoName, prNumber, r.ID); err != nil {
+						log.Printf("Warning: could not delete old review %d: %v", r.ID, err)
+					} else {
+						log.Printf("Deleted stale review %d", r.ID)
 					}
 				}
 			}
 		}
 	}
-
-	log.Printf("Posting review (event=%s)...", event)
-	if err := giteaClient.PostReview(ctx, owner, repoName, prNumber, event, reviewBody); err != nil {
-		log.Fatalf("Failed to post review: %v", err)
-	}
-	log.Printf("Review posted successfully!")
 }
 
 // fetchFileContext fetches the full content of modified files from the PR branch.
@@ -359,7 +355,7 @@ func envOrDefaultInt(key string, defaultVal int) int {
 }
 
 func envOrDefaultBool(key string, defaultVal bool) bool {
-	v := os.Getenv(key)
+	v := strings.TrimSpace(strings.ToLower(os.Getenv(key)))
 	if v == "" {
 		return defaultVal
 	}