feat: slim tool responses (#141)

Reduce token usage by slimming tool responses. Instead of returning full Gitea SDK objects (with nested user/repo objects, avatars, permissions, etc.), each operation now has a colocated `slim.go` that extracts only the fields an LLM needs. List endpoints return even fewer fields than single-item endpoints.

Other changes:
- Add `params` helpers to DRY parameter extraction across 40+ handlers
- Remove `{"Result": ...}` wrapper for flatter responses
- Reduce default pageSize from 100 to 30

Fixes: https://gitea.com/gitea/gitea-mcp/issues/128

*Created by Claude on behalf of @silverwind*

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/141
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

operation/repo/slim.go

@@ -0,0 +1,201 @@
+package repo
+
+import (
+	gitea_sdk "code.gitea.io/sdk/gitea"
+)
+
+func userLogin(u *gitea_sdk.User) string {
+	if u == nil {
+		return ""
+	}
+	return u.UserName
+}
+
+func slimRepo(r *gitea_sdk.Repository) map[string]any {
+	if r == nil {
+		return nil
+	}
+	m := map[string]any{
+		"id":                r.ID,
+		"full_name":         r.FullName,
+		"description":       r.Description,
+		"html_url":          r.HTMLURL,
+		"clone_url":         r.CloneURL,
+		"ssh_url":           r.SSHURL,
+		"default_branch":    r.DefaultBranch,
+		"private":           r.Private,
+		"fork":              r.Fork,
+		"archived":          r.Archived,
+		"language":          r.Language,
+		"stars_count":       r.Stars,
+		"forks_count":       r.Forks,
+		"open_issues_count": r.OpenIssues,
+		"open_pr_counter":   r.OpenPulls,
+		"created_at":        r.Created,
+		"updated_at":        r.Updated,
+	}
+	if r.Owner != nil {
+		m["owner"] = r.Owner.UserName
+	}
+	if len(r.Topics) > 0 {
+		m["topics"] = r.Topics
+	}
+	return m
+}
+
+func slimRepos(repos []*gitea_sdk.Repository) []map[string]any {
+	out := make([]map[string]any, 0, len(repos))
+	for _, r := range repos {
+		out = append(out, slimRepo(r))
+	}
+	return out
+}
+
+func slimBranch(b *gitea_sdk.Branch) map[string]any {
+	if b == nil {
+		return nil
+	}
+	m := map[string]any{
+		"name":      b.Name,
+		"protected": b.Protected,
+	}
+	if b.Commit != nil {
+		m["commit_sha"] = b.Commit.ID
+	}
+	return m
+}
+
+func slimBranches(branches []*gitea_sdk.Branch) []map[string]any {
+	out := make([]map[string]any, 0, len(branches))
+	for _, b := range branches {
+		out = append(out, slimBranch(b))
+	}
+	return out
+}
+
+func slimCommit(c *gitea_sdk.Commit) map[string]any {
+	if c == nil {
+		return nil
+	}
+	m := map[string]any{
+		"sha":      c.SHA,
+		"html_url": c.HTMLURL,
+		"created":  c.Created,
+	}
+	if c.RepoCommit != nil {
+		m["message"] = c.RepoCommit.Message
+		if c.RepoCommit.Author != nil {
+			m["author"] = map[string]any{
+				"name":  c.RepoCommit.Author.Name,
+				"email": c.RepoCommit.Author.Email,
+				"date":  c.RepoCommit.Author.Date,
+			}
+		}
+	}
+	return m
+}
+
+func slimCommits(commits []*gitea_sdk.Commit) []map[string]any {
+	out := make([]map[string]any, 0, len(commits))
+	for _, c := range commits {
+		out = append(out, slimCommit(c))
+	}
+	return out
+}
+
+func slimTag(t *gitea_sdk.Tag) map[string]any {
+	if t == nil {
+		return nil
+	}
+	m := map[string]any{
+		"name":    t.Name,
+		"message": t.Message,
+	}
+	if t.Commit != nil {
+		m["commit_sha"] = t.Commit.SHA
+	}
+	return m
+}
+
+func slimTags(tags []*gitea_sdk.Tag) []map[string]any {
+	out := make([]map[string]any, 0, len(tags))
+	for _, t := range tags {
+		m := map[string]any{
+			"name": t.Name,
+		}
+		if t.Commit != nil {
+			m["commit_sha"] = t.Commit.SHA
+		}
+		out = append(out, m)
+	}
+	return out
+}
+
+func slimRelease(r *gitea_sdk.Release) map[string]any {
+	if r == nil {
+		return nil
+	}
+	return map[string]any{
+		"id":           r.ID,
+		"tag_name":     r.TagName,
+		"target":       r.Target,
+		"title":        r.Title,
+		"body":         r.Note,
+		"draft":        r.IsDraft,
+		"prerelease":   r.IsPrerelease,
+		"html_url":     r.HTMLURL,
+		"author":       userLogin(r.Publisher),
+		"created_at":   r.CreatedAt,
+		"published_at": r.PublishedAt,
+	}
+}
+
+func slimReleases(releases []*gitea_sdk.Release) []map[string]any {
+	out := make([]map[string]any, 0, len(releases))
+	for _, r := range releases {
+		out = append(out, slimRelease(r))
+	}
+	return out
+}
+
+func slimContents(c *gitea_sdk.ContentsResponse) map[string]any {
+	if c == nil {
+		return nil
+	}
+	m := map[string]any{
+		"name": c.Name,
+		"path": c.Path,
+		"sha":  c.SHA,
+		"type": c.Type,
+		"size": c.Size,
+	}
+	if c.Content != nil {
+		m["content"] = *c.Content
+	}
+	if c.Encoding != nil {
+		m["encoding"] = *c.Encoding
+	}
+	if c.HTMLURL != nil {
+		m["html_url"] = *c.HTMLURL
+	}
+	if c.DownloadURL != nil {
+		m["download_url"] = *c.DownloadURL
+	}
+	return m
+}
+
+func slimDirEntries(entries []*gitea_sdk.ContentsResponse) []map[string]any {
+	out := make([]map[string]any, 0, len(entries))
+	for _, c := range entries {
+		if c == nil {
+			continue
+		}
+		out = append(out, map[string]any{
+			"name": c.Name,
+			"path": c.Path,
+			"type": c.Type,
+			"size": c.Size,
+		})
+	}
+	return out
+}