feat(ssh-keys): add ssh-keys command to manage SSH public keys (#940)

## Summary

- Adds `tea ssh-keys` command group (aliases: `ssh-key`, `keys`) under the SETUP category
- Mirrors the interface of `gh ssh-key add/list/delete`
- Three subcommands: `add <keyfile>`, `list`, `delete <id>`

## Commands

\`\`\`sh
tea ssh-keys add ~/.ssh/id_ed25519.pub                     # title defaults to filename stem
tea ssh-keys add ~/.ssh/id_rsa.pub --title "work laptop"
tea ssh-keys add ~/.ssh/deploy.pub --read-only             # authentication-only key
tea ssh-keys list
tea ssh-keys list --output json
tea ssh-keys delete 42                                     # prompts for confirmation
tea ssh-keys delete 42 --force                             # skip prompt
\`\`\`

## Test plan

- [x] `make lint` — 0 issues
- [x] `make fmt-check` — passes
- [x] `go test ./cmd/sshkeys/... -run TestKeyTitle` — unit tests pass (no server needed)
- [ ] Integration tests with live Gitea instance:
  \`\`\`sh
  GITEA_TEA_TEST_URL=https://your-gitea \
  GITEA_TEA_TEST_TOKEN=<token> \
  go test ./cmd/sshkeys/... -v -run TestSSHKey
  \`\`\`
  Exercises full add → SDK-verify → delete → 404-verify lifecycle.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Brandon Fryslie <530235+brandon-fryslie@users.noreply.github.com>
Reviewed-on: https://gitea.com/gitea/tea/pulls/940
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Brandon Fryslie <186614+brandroid@noreply.gitea.com>
Co-committed-by: Brandon Fryslie <186614+brandroid@noreply.gitea.com>

cmd/sshkeys/list.go

@@ -0,0 +1,47 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package sshkeys
+
+import (
+	stdctx "context"
+
+	"code.gitea.io/sdk/gitea"
+	"code.gitea.io/tea/cmd/flags"
+	"code.gitea.io/tea/modules/context"
+	"code.gitea.io/tea/modules/print"
+
+	"github.com/urfave/cli/v3"
+)
+
+// CmdSSHKeyList represents a sub command of ssh-keys to list the current user's SSH keys
+var CmdSSHKeyList = cli.Command{
+	Name:        "list",
+	Aliases:     []string{"ls"},
+	Usage:       "List SSH keys",
+	Description: "List the SSH keys registered for the current user",
+	ArgsUsage:   " ", // command does not accept arguments
+	Action:      RunSSHKeyList,
+	Flags: append([]cli.Flag{
+		&flags.PaginationPageFlag,
+		&flags.PaginationLimitFlag,
+	}, flags.LoginOutputFlags...),
+}
+
+// RunSSHKeyList lists SSH keys for the current user
+func RunSSHKeyList(_ stdctx.Context, cmd *cli.Command) error {
+	ctx, err := context.InitCommand(cmd)
+	if err != nil {
+		return err
+	}
+	client := ctx.Login.Client()
+
+	keys, _, err := client.ListMyPublicKeys(gitea.ListPublicKeysOptions{
+		ListOptions: flags.GetListOptions(cmd),
+	})
+	if err != nil {
+		return err
+	}
+
+	return print.SSHKeysList(keys, ctx.Output)
+}