feat: multi-repo patterns + directory recursion

patterns-repo now accepts a comma-separated list of repos:
  PATTERNS_REPO="rodin/elixir-patterns,rodin/phoenix-conventions"

patterns-files accepts files AND directories:
  PATTERNS_FILES="README.md,docs/"

When a path is a directory, all files within it are fetched
recursively via the Gitea contents API. Only .md, .txt, .yml,
and .yaml files are included as pattern content.

New API methods:
- ListContents: list files/dirs at a path via contents API
- GetAllFilesInPath: recursively fetch all file contents

This allows a single review action to pull idioms from multiple
pattern repos (e.g. elixir-patterns + phoenix-conventions) and
include entire directories of documentation as review criteria.

cmd/review-bot/main.go

@@ -184,31 +184,61 @@ func fetchFileContext(client *gitea.Client, owner, repo, ref string, files []git
 	return sb.String()
 }
 
-// fetchPatterns fetches pattern files from an external repo.
+// fetchPatterns fetches pattern files from one or more external repos.
+// patternsRepo is comma-separated list of owner/name repos.
+// patternsFiles is comma-separated list of file paths or directories.
+// If a path ends with / or is a directory, all files within it are fetched recursively.
 func fetchPatterns(client *gitea.Client, patternsRepo, patternsFiles string) string {
-	parts := strings.SplitN(patternsRepo, "/", 2)
-	if len(parts) != 2 {
-		log.Printf("Warning: invalid patterns-repo format %q, expected owner/name", patternsRepo)
-		return ""
-	}
-	owner, repo := parts[0], parts[1]
-
 	var sb strings.Builder
-	for _, filepath := range strings.Split(patternsFiles, ",") {
-		filepath = strings.TrimSpace(filepath)
-		if filepath == "" {
+
+	repos := strings.Split(patternsRepo, ",")
+	paths := strings.Split(patternsFiles, ",")
+
+	for _, repoRef := range repos {
+		repoRef = strings.TrimSpace(repoRef)
+		if repoRef == "" {
 			continue
 		}
-		content, err := client.GetFileContent(owner, repo, filepath)
-		if err != nil {
-			log.Printf("Warning: could not fetch pattern file %s from %s: %v", filepath, patternsRepo, err)
+		parts := strings.SplitN(repoRef, "/", 2)
+		if len(parts) != 2 {
+			log.Printf("Warning: invalid patterns-repo format %q, expected owner/name", repoRef)
 			continue
 		}
-		sb.WriteString(fmt.Sprintf("### %s/%s\n\n%s\n\n", patternsRepo, filepath, content))
+		owner, repo := parts[0], parts[1]
+
+		for _, path := range paths {
+			path = strings.TrimSpace(path)
+			if path == "" {
+				continue
+			}
+
+			files, err := client.GetAllFilesInPath(owner, repo, path)
+			if err != nil {
+				log.Printf("Warning: could not fetch %s from %s: %v", path, repoRef, err)
+				continue
+			}
+
+			for filepath, content := range files {
+				// Only include markdown and text files as patterns
+				if !isPatternFile(filepath) {
+					continue
+				}
+				sb.WriteString(fmt.Sprintf("### %s/%s\n\n%s\n\n", repoRef, filepath, content))
+			}
+		}
 	}
 	return sb.String()
 }
 
+// isPatternFile returns true if the file should be included as pattern content.
+func isPatternFile(path string) bool {
+	lower := strings.ToLower(path)
+	return strings.HasSuffix(lower, ".md") ||
+		strings.HasSuffix(lower, ".txt") ||
+		strings.HasSuffix(lower, ".yml") ||
+		strings.HasSuffix(lower, ".yaml")
+}
+
 // evaluateCIStatus checks if all CI statuses indicate success.
 func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details string) {
 	if len(statuses) == 0 {