refactor: add terminal output and forms package (#1124)

- `internal/terminal`: streams and the prompting policy, interactive forms (issue, PR, review, merge, milestone), editor / pager / browser launching, JSON and `--jq` output.
- An aligned table renderer and a record renderer for human output; both strip control and escape characters from server-supplied text so titles and bodies cannot inject terminal sequences.

Reviewed-on: https://gitea.com/gitea/tea/pulls/1124
Reviewed-by: TheFox0x7 <95654+thefox0x7@noreply.gitea.com>

internal/terminal/color.go

@@ -0,0 +1,62 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package terminal
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+// ColorEnabled resolves the color preference against terminal and environment policy.
+// auto colors TTY stdout unless NO_COLOR is set or TERM is dumb; always forces color; never disables it.
+func ColorEnabled(preference string, outTTY bool, getenv func(string) string) bool {
+	switch preference {
+	case "always":
+		return true
+	case "never":
+		return false
+	default: // auto and unknown fall back to terminal detection
+		if getenv != nil && (getenv("NO_COLOR") != "" || getenv("TERM") == "dumb") {
+			return false
+		}
+		return outTTY
+	}
+}
+
+// Colorize applies a 24-bit foreground color from a six-digit RGB hex value.
+func Colorize(hex, text string, enabled bool) string {
+	if !enabled || text == "" {
+		return text
+	}
+	hex = strings.TrimPrefix(strings.TrimSpace(hex), "#")
+	if len(hex) != 6 {
+		return text
+	}
+	r, errR := strconv.ParseUint(hex[0:2], 16, 8)
+	g, errG := strconv.ParseUint(hex[2:4], 16, 8)
+	b, errB := strconv.ParseUint(hex[4:6], 16, 8)
+	if errR != nil || errG != nil || errB != nil {
+		return text
+	}
+	return fmt.Sprintf("\x1b[38;2;%d;%d;%dm%s\x1b[0m", r, g, b, text)
+}
+
+// Emphasis applies simple bold styling for TTY human tables.
+func Emphasis(text string, enabled bool) string {
+	if !enabled || text == "" {
+		return text
+	}
+	return "\x1b[1m" + text + "\x1b[0m"
+}
+
+// Hyperlink wraps text in an OSC 8 terminal hyperlink to url. URLs with control
+// characters are left unlinked so server data cannot inject escape sequences.
+func Hyperlink(url, text string, enabled bool) string {
+	if !enabled || url == "" || text == "" || strings.ContainsFunc(url, unicode.IsControl) {
+		return text
+	}
+	return "\x1b]8;;" + url + "\x1b\\" + text + "\x1b]8;;\x1b\\"
+}