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>

modules/print/sshkey.go

@@ -0,0 +1,44 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package print
+
+import (
+	"fmt"
+
+	"code.gitea.io/sdk/gitea"
+)
+
+// SSHKeysList prints a table of SSH public keys
+func SSHKeysList(keys []*gitea.PublicKey, output string) error {
+	if len(keys) == 0 {
+		fmt.Printf("No SSH keys found\n")
+		return nil
+	}
+
+	t := tableWithHeader(
+		"ID",
+		"Title",
+		"Fingerprint",
+		"KeyType",
+		"ReadOnly",
+		"Created",
+	)
+
+	for _, k := range keys {
+		readOnly := "false"
+		if k.ReadOnly {
+			readOnly = "true"
+		}
+		t.addRow(
+			fmt.Sprintf("%d", k.ID),
+			k.Title,
+			k.Fingerprint,
+			k.KeyType,
+			readOnly,
+			FormatTime(k.Created, false),
+		)
+	}
+
+	return t.print(output)
+}