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/actions/slim.go

@@ -0,0 +1,92 @@
+package actions
+
+func pick(m map[string]any, keys ...string) map[string]any {
+	out := make(map[string]any, len(keys))
+	for _, k := range keys {
+		if v, ok := m[k]; ok {
+			out[k] = v
+		}
+	}
+	return out
+}
+
+func slimPaginated(raw any, itemFn func(map[string]any) map[string]any) any {
+	m, ok := raw.(map[string]any)
+	if !ok {
+		return raw
+	}
+	result := make(map[string]any)
+	if tc, ok := m["total_count"]; ok {
+		result["total_count"] = tc
+	}
+	for key, val := range m {
+		if key == "total_count" {
+			continue
+		}
+		arr, ok := val.([]any)
+		if !ok {
+			continue
+		}
+		slimmed := make([]any, 0, len(arr))
+		for _, item := range arr {
+			if im, ok := item.(map[string]any); ok {
+				slimmed = append(slimmed, itemFn(im))
+			}
+		}
+		result[key] = slimmed
+		break
+	}
+	return result
+}
+
+func slimRun(m map[string]any) map[string]any {
+	return pick(m, "id", "name", "head_branch", "head_sha", "run_number",
+		"event", "status", "conclusion", "workflow_id",
+		"html_url", "created_at", "updated_at")
+}
+
+func slimJob(m map[string]any) map[string]any {
+	out := pick(m, "id", "run_id", "name", "workflow_name",
+		"status", "conclusion", "html_url",
+		"started_at", "completed_at")
+	if steps, ok := m["steps"].([]any); ok {
+		slim := make([]any, 0, len(steps))
+		for _, s := range steps {
+			if sm, ok := s.(map[string]any); ok {
+				slim = append(slim, pick(sm, "name", "number", "status", "conclusion"))
+			}
+		}
+		out["steps"] = slim
+	}
+	return out
+}
+
+func slimWorkflow(m map[string]any) map[string]any {
+	return pick(m, "id", "name", "path", "state", "html_url", "created_at", "updated_at")
+}
+
+func slimActionRun(raw any) any {
+	if m, ok := raw.(map[string]any); ok {
+		return slimRun(m)
+	}
+	return raw
+}
+
+func slimActionRuns(raw any) any {
+	return slimPaginated(raw, slimRun)
+}
+
+func slimActionJobs(raw any) any {
+	return slimPaginated(raw, slimJob)
+}
+
+func slimActionWorkflow(raw any) any {
+	if m, ok := raw.(map[string]any); ok {
+		return slimWorkflow(m)
+	}
+	return raw
+}
+
+func slimActionWorkflows(raw any) any {
+	return slimPaginated(raw, slimWorkflow)
+}