feat: inline review comments on specific lines

Findings that reference a file+line within the diff are now posted as
inline comments directly on that line, in addition to appearing in the
summary table. Findings outside the diff range stay in the body only.

Implementation:
- gitea/diff.go: ParseDiffNewLines extracts new-file line numbers from
  each hunk in the unified diff
- gitea/client.go: PostReview accepts optional []ReviewComment with
  path + new_position + body (omitempty when nil)
- cmd/review-bot/main.go: maps findings → inline comments when the line
  exists in the diff, passes them to PostReview

Tests:
- diff parser: multi-hunk, new files, empty diff, boundary lines
- PostReview: with comments, nil comments (omitted from payload)

gitea/client.go

@@ -57,6 +57,13 @@ type ChangedFile struct {
 	Status   string `json:"status"`
 }
 
+// ReviewComment represents an inline comment to attach to a review.
+type ReviewComment struct {
+	Path        string `json:"path"`
+	NewPosition int64  `json:"new_position"`
+	Body        string `json:"body"`
+}
+
 // GetPullRequest fetches PR metadata.
 func (c *Client) GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error) {
 	reqURL := fmt.Sprintf("%s/api/v1/repos/%s/%s/pulls/%d", c.baseURL, owner, repo, number)
@@ -131,15 +138,18 @@ func (c *Client) GetFileContentRef(ctx context.Context, owner, repo, filepath, r
 
 // PostReview submits a review to a PR and returns the created review.
 // event should be "APPROVED" or "REQUEST_CHANGES".
-func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body string) (*Review, error) {
+// comments are optional inline comments attached to specific lines.
+func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body string, comments []ReviewComment) (*Review, error) {
 	reqURL := fmt.Sprintf("%s/api/v1/repos/%s/%s/pulls/%d/reviews", c.baseURL, owner, repo, number)
 
 	payload := struct {
-		Body  string `json:"body"`
-		Event string `json:"event"`
+		Body     string          `json:"body"`
+		Event    string          `json:"event"`
+		Comments []ReviewComment `json:"comments,omitempty"`
 	}{
-		Body:  body,
-		Event: event,
+		Body:     body,
+		Event:    event,
+		Comments: comments,
 	}
 
 	data, err := json.Marshal(payload)