Make tea issues create honor --output json (#1114)

## Problem

Follow-up to #1111, covering the issues side of the same hole: `tea issues create` accepts `--output` (it parses through the urfave/cli v3 ancestor-flag cascade — `issues` carries the flag via `AllDefaultFlags`, `create` never declares it) but the action never reads it. Without this fix, `tea issues create --output json | jq .url` feeds jq a markdown document.

The default output is doubly hostile to consumers: glamour renders the details as markdown (with OSC 8 hyperlinks around the URL when piped), and a second bare `fmt.Println(issue.HTMLURL)` line follows it.

## What this changes

- `task.CreateIssue` now returns the created `*gitea.Issue` instead of printing it.
- `runIssuesCreate` switches on `--output`, mirroring the detail-command precedent and the merged create-PR behavior from #1111: `--output json` emits compact lean JSON; any other value (or no flag) falls through to the previous rendering, byte-identical to before.
- Lean JSON shape: `index`, `title`, `url`, `state` — matching `createdPullJSON` in `cmd/pulls/create.go`, including its post-review compact encoding.
- The interactive path is untouched — it only triggers when zero flags are set, so `--output` can never be active there.

Example:

```
$ tea issues create --output json --title "bug: thing" | jq -r .url
https://gitea.example.com/owner/repo/issues/42
```

There is no agit-flow equivalent on issues, so no extra guard is needed — unlike the pulls side, every creation path produces an `*gitea.Issue`.

---------

Co-authored-by: Danilo Sousa <code@danilosousa.net>
Reviewed-on: https://gitea.com/gitea/tea/pulls/1114
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: ongolk <238961+ongolk@noreply.gitea.com>

modules/task/issue_create.go

@@ -10,24 +10,19 @@ import (
 	gitea "gitea.dev/sdk"
 
 	"gitea.dev/tea/modules/config"
-	"gitea.dev/tea/modules/print"
 )
 
-// CreateIssue creates an issue in the given repo and prints the result
-func CreateIssue(requestCtx stdctx.Context, rlogin *config.Login, repoOwner, repoName string, opts gitea.CreateIssueOption) error {
+// CreateIssue creates an issue in the given repo and returns the created issue
+func CreateIssue(requestCtx stdctx.Context, rlogin *config.Login, repoOwner, repoName string, opts gitea.CreateIssueOption) (*gitea.Issue, error) {
 	// title is required
 	if len(opts.Title) == 0 {
-		return fmt.Errorf("title is required")
+		return nil, fmt.Errorf("title is required")
 	}
 
 	issue, _, err := rlogin.Client().Issues.CreateIssue(requestCtx, repoOwner, repoName, opts)
 	if err != nil {
-		return fmt.Errorf("could not create issue: %s", err)
+		return nil, fmt.Errorf("could not create issue: %s", err)
 	}
 
-	print.IssueDetails(issue, nil)
-
-	fmt.Println(issue.HTMLURL)
-
-	return nil
+	return issue, nil
 }