Make tea pulls create honor --output json (#1111)

## Problem

`tea pulls create` accepts `--output` (the flag parses successfully) but never reads it — the action always prints glamour-rendered markdown regardless of the requested format. That is a trap for anyone scripting the CLI: `tea pr create --output json | jq .url` quietly feeds jq a markdown document.

The current output is also hostile to URL-scraping consumers even without `--output`: glamour autolinks the bare PR URL into an OSC 8 terminal hyperlink, so piped stdout contains

```
\x1b]8;;https://host/owner/repo/pulls/33\x1b\\https://host/owner/repo/pulls/33\x1b]8;;\x1b\\
```

instead of a plain URL (repro: `tea pr create ... | cat -v`).

## Why the flag parses but does nothing

`create` itself does not declare `--output`: its flag set (`IssuePRCreateFlags`) carries no `OutputFlag`. The flag parses anyway because urfave/cli v3 resolves flags through `Command.lookupAppliedFlag`, which searches `appliedFlags` — "local flags for current command **or persistent flags from ancestors**". The parent `pulls` command carries `--output` via `AllDefaultFlags`, so the flag reaches the subcommand's parser while being absent from `create --help` — and was never consulted by the action.

## What this changes

- `task.CreatePull` now returns the created `*gitea.PullRequest` instead of printing it.
- `runPullsCreate` switches on `--output`, mirroring the existing detail-command precedent (`RunPullsDetails` in `cmd/pulls.go`): `--output json` emits a lean JSON object; any other value (or no flag at all) falls through to the previous `print.PullDetails` rendering, byte-identical to before.
- Lean JSON shape, since a freshly created PR has no reviews/comments/CI yet: `index`, `title`, `url`, `state`, `base`, `head`.
- `--agit` combined with `--output` now fails fast with an explicit error before any API call or `git push`: the agit flow creates the PR server-side via push and returns no object to print.
- The interactive path is untouched — it only triggers when zero flags are set, so `--output` can never be active there.

Example:

```
$ tea pr create --output json --title "fix: thing" | jq -r .url
https://gitea.example.com/owner/repo/pulls/33
```

---------

Co-authored-by: Danilo Sousa <code@danilosousa.net>
Reviewed-on: https://gitea.com/gitea/tea/pulls/1111
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: ongolk <238961+ongolk@noreply.gitea.com>

cmd/pulls/create.go

@@ -5,6 +5,9 @@ package pulls
 
 import (
 	stdctx "context"
+	"encoding/json"
+	"fmt"
+	"io"
 
 	gitea "gitea.dev/sdk"
 	"github.com/urfave/cli/v3"
@@ -12,6 +15,7 @@ import (
 	"gitea.dev/tea/cmd/flags"
 	"gitea.dev/tea/modules/context"
 	"gitea.dev/tea/modules/interact"
+	"gitea.dev/tea/modules/print"
 	"gitea.dev/tea/modules/task"
 	"gitea.dev/tea/modules/utils"
 )
@@ -80,6 +84,12 @@ func runPullsCreate(requestCtx stdctx.Context, cmd *cli.Command) error {
 		return nil
 	}
 
+	// agit flow creates the PR via git push and returns no PR object, so
+	// --output cannot be honored there; fail fast before any API calls
+	if ctx.Bool("agit") && ctx.IsSet("output") {
+		return fmt.Errorf("--output cannot be combined with --agit: the PR is created via git push, so no pull request object is available to print")
+	}
+
 	// else use args to create PR
 	opts, err := flags.GetIssuePRCreateFlags(requestCtx, ctx)
 	if err != nil {
@@ -108,7 +118,7 @@ func runPullsCreate(requestCtx stdctx.Context, cmd *cli.Command) error {
 		allowMaintainerEdits = gitea.OptionalBool(ctx.Bool("allow-maintainer-edits"))
 	}
 
-	return task.CreatePull(
+	pr, err := task.CreatePull(
 		requestCtx,
 		ctx,
 		ctx.String("base"),
@@ -116,4 +126,41 @@ func runPullsCreate(requestCtx stdctx.Context, cmd *cli.Command) error {
 		allowMaintainerEdits,
 		opts,
 	)
+	if err != nil {
+		return err
+	}
+
+	if ctx.IsSet("output") {
+		switch ctx.String("output") {
+		case "json":
+			return writeCreatedPullAsJSON(ctx.Writer, pr)
+		}
+	}
+
+	print.PullDetails(pr, nil, nil)
+
+	return nil
+}
+
+// createdPullJSON is the machine-readable representation of a freshly
+// created pull request. A new PR has no reviews, comments or CI yet, so
+// this is intentionally leaner than the detail view's pullData (cmd/pulls.go).
+type createdPullJSON struct {
+	Index int64           `json:"index"`
+	Title string          `json:"title"`
+	URL   string          `json:"url"`
+	State gitea.StateType `json:"state"`
+	Base  string          `json:"base"`
+	Head  string          `json:"head"`
+}
+
+func writeCreatedPullAsJSON(w io.Writer, pr *gitea.PullRequest) error {
+	return json.NewEncoder(w).Encode(createdPullJSON{
+		Index: pr.Index,
+		Title: pr.Title,
+		URL:   pr.HTMLURL,
+		State: pr.State,
+		Base:  pr.Base.Ref,
+		Head:  pr.Head.Ref,
+	})
 }