Inline issue/comment attachments in body (#183)

The Gitea API returns an `assets` array on issue and comment responses, but the SDK structs drop it — so attachments are invisible to MCP agents.

Append each attachment as a `[name](url)` markdown link at the end of the body, mirroring how GitHub embeds attachments inline (which `github-mcp-server` preserves as-is).

**Coverage:**
- `issue_read get` — issue body attachments
- `issue_read get_comments` — issue and PR conversation comment attachments (same endpoint)
- `pull_request_read get` — PR description attachments (Gitea's `/pulls/` endpoint omits `assets`, so a follow-up best-effort call to `/issues/{n}/assets` surfaces them; PRs are issues internally)

PR review summaries and line-comment reviews don't support attachments per the Gitea API spec, so nothing to do there.

Closes https://gitea.com/gitea/gitea-mcp/issues/182

---
This PR was written with the help of Claude Opus 4.7

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/183
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

operation/pull/slim.go

@@ -1,9 +1,30 @@
 package pull
 
 import (
+	"fmt"
+	"strings"
+
 	gitea_sdk "code.gitea.io/sdk/gitea"
 )
 
+func bodyWithAttachments(body string, atts []*gitea_sdk.Attachment) string {
+	links := make([]string, 0, len(atts))
+	for _, a := range atts {
+		if a == nil || a.DownloadURL == "" {
+			continue
+		}
+		links = append(links, fmt.Sprintf("[%s](%s)", a.Name, a.DownloadURL))
+	}
+	if len(links) == 0 {
+		return body
+	}
+	joined := strings.Join(links, "\n")
+	if body == "" {
+		return joined
+	}
+	return body + "\n\n" + joined
+}
+
 func userLogin(u *gitea_sdk.User) string {
 	if u == nil {
 		return ""