feat(web): visual rule builder with geo, CIDR and wildcard pickers

The rule editor no longer requires writing expr by hand. Conditions are rows of
field + operator + values joined with AND or OR, each row negatable, and the
generated expression is shown live and validated by the engine before a rule is
accepted. Raw expression and YAML editing are still available.

Fields cover the connection (protocol, source/destination IP and port), domains
(TLS SNI, QUIC SNI, DNS query name), HTTP (host, path, method, User-Agent) and
protocol detection. Operators cover CIDR membership, GeoIP countries, GeoSite
categories, port ranges, wildcards, substrings and regular expressions.
Multiple values in a row are OR-ed, so one row holds a whole domain or country
list.

Wildcards compile to the cheapest expression that matches them: *.x.com
becomes endsWith, x.* startsWith, *ad* contains, and only a star in the
middle falls back to a regular expression. Values are validated as they are
typed, including a hint when a star is used with an operator that would match
it literally.

Country and category pickers are backed by the databases the engine actually
loaded, via a new GET /api/v1/geo endpoint (cached, loaded on demand) built on
new listing methods in the geo package. Country names and flags come from
Intl.DisplayNames, so no name table is shipped. Note that the v2geo format has
no AS numbers; the provider groups it does contain (cloudflare, google,
telegram, ...) are listed alongside the countries.

Opening an existing rule parses its expression back into conditions. Anything
the builder cannot represent opens in the expression editor with a warning
rather than being rewritten. ruleset/expr_test.go pins the canonical
expressions the builder generates and compiles them with the real engine, and
the devserver now uses the real ruleset compiler so the same errors show up
during frontend work.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.ja.md

@@ -37,6 +37,10 @@ OpenGFW にはオプションのウェブダッシュボードが同梱されて
 アナライザのプロパティを含むイベントフィード、そしてルールを検証してホットリロードできるルールエディタが利用できます。
 スマートフォンでもデスクトップでも使えるレスポンシブ対応です。
 
+ルールは条件のリストとして作成できます。フィールド（SNI、DNS 名、HTTP Host、IP、ポート、検出されたプロトコル）と
+条件（ワイルドカード、CIDR、GeoIP の国、GeoSite カテゴリ、範囲、正規表現）、そして 1 つ以上の値を選ぶだけです。
+もちろん expr 式や YAML を直接編集することもできます。
+
 設定ファイルで有効にします:
 
 ```yaml