feat: issue_list + workflow_run_list tools (#28, #29)

Adds the *_list partners that the existing *_get tools have been
missing. Same pattern as repo_list — owner allowlisted, capLimit
helper for pagination, next_page surfaced when the page is full.

internal/gitea/issues.go:
- ListIssues(owner, repo, args) hitting
  GET /api/v1/repos/{owner}/{repo}/issues with type=issues server-side
  so PRs don't leak in (gitea conflates them on this endpoint).
- ListIssuesArgs struct: State, Labels, Since (ISO 8601), Page, Limit.

internal/gitea/workflows.go:
- ListWorkflowRuns(owner, repo, args) hitting
  GET /api/v1/repos/{owner}/{repo}/actions/runs.
- Expanded WorkflowRun struct with DisplayTitle, Event, HeadSHA,
  HeadBranch, WorkflowID, RunNumber, UpdatedAt, Actor so callers
  can pin runs to a commit / branch without a second lookup.
- ListWorkflowRunsArgs: Branch, HeadSHA, Status, Event, Workflow,
  Page, Limit. Status/Event 'all' treated as no-filter.

internal/tools/issue_list.go:
- Default state=open, default limit=30 (matches repo_list).
- next_page returned only when len(issues) == limit.

internal/tools/workflow_run_list.go:
- Default limit=10 (most common use is 'what just happened',
  not paging).
- Returns runs + total + optional next_page.

Tests: table-driven for both — happy path, empty result, filter
combinations, allowlist rejection. workflow_run_list also asserts
the 'status=all is no-op' behavior (no query param emitted).

Closes #28
Closes #29

internal/gitea/issues.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"net/url"
+	"strconv"
 )
 
 type Issue struct {
@@ -72,6 +74,50 @@ func (c *Client) CreateIssue(ctx context.Context, owner, repo string, args Creat
 	return &iss, nil
 }
 
+// ListIssuesArgs captures the optional query params for ListIssues.
+type ListIssuesArgs struct {
+	State  string // "open" | "closed" | "all"
+	Labels string // comma-separated label names
+	Since  string // ISO 8601
+	Page   int
+	Limit  int
+}
+
+// ListIssues fetches issues for a repo. Pulls are excluded server-side
+// (type=issues) so they don't leak through the same endpoint.
+func (c *Client) ListIssues(ctx context.Context, owner, repo string, args ListIssuesArgs) ([]Issue, error) {
+	q := url.Values{}
+	q.Set("type", "issues")
+	if args.State != "" {
+		q.Set("state", args.State)
+	}
+	if args.Labels != "" {
+		q.Set("labels", args.Labels)
+	}
+	if args.Since != "" {
+		q.Set("since", args.Since)
+	}
+	if args.Page > 0 {
+		q.Set("page", strconv.Itoa(args.Page))
+	}
+	if args.Limit > 0 {
+		q.Set("limit", strconv.Itoa(args.Limit))
+	}
+	p := fmt.Sprintf("/api/v1/repos/%s/%s/issues?%s", owner, repo, q.Encode())
+	body, status, err := c.GetJSON(ctx, p)
+	if err != nil {
+		return nil, err
+	}
+	if err := MapStatus(status, body); err != nil {
+		return nil, err
+	}
+	var issues []Issue
+	if err := json.Unmarshal(body, &issues); err != nil {
+		return nil, err
+	}
+	return issues, nil
+}
+
 // SetIssueState flips an issue between "open" and "closed" via PATCH.
 // Gitea uses the same endpoint for both transitions.
 func (c *Client) SetIssueState(ctx context.Context, owner, repo string, number int, state string) (*Issue, error) {