Gitea API rejects "." with HTTP 500 (malformed path component).
When patterns-files is set to ".", normalize it to empty string
before making the API call.

Fixes #70

@@ -437,1 +437,4 @@
 func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error) {
+	// Normalize "." to empty string — Gitea API rejects "." with 500
+	if path == "." {
+		path = ""

@@ -67,1 +67,4 @@
         run: ./review-bot
+
+  # Test dot path normalization with security-patterns repo
+  test-dot-path:

@@ -435,6 +435,10 @@ type ContentEntry struct {
 // ListContents lists files and directories at a given path in a repo.
 // Pass an empty path to list the repository root.
 func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error) {
+	// Normalize "." to empty string — Gitea API rejects "." with 500

@@ -66,2 +66,4 @@
           SYSTEM_PROMPT_FILE: ${{ matrix.system_prompt_file }}
         run: ./review-bot
+
+  # Test dot path normalization with security-patterns repo

@@ -435,6 +435,10 @@ type ContentEntry struct {
 // ListContents lists files and directories at a given path in a repo.

@@ -65,3 +65,34 @@ jobs:
           LLM_TIMEOUT: "600"

@@ -435,6 +435,10 @@ type ContentEntry struct {
 // ListContents lists files and directories at a given path in a repo.

@@ -435,6 +435,10 @@ type ContentEntry struct {
 // ListContents lists files and directories at a given path in a repo.
 // Pass an empty path to list the repository root.