feat: Support relays and naddrs sets

This commit introduces support for 'sets', a feature that simplifies
referencing multiple relays or naddrs with a single word.

Sets are stored in the config directory under `n34` as `config.toml` in
`TOML` format. The config path follows the `$XDG_CONFIG_HOME` standard,
defaulting to `$HOME/.config` if unset.

The `n34 sets` command allows managing sets, adding, removing, updating,
or displaying them. When using the main `--relays` flag, a set name can
be provided to automatically expand its relays (an error occurs if the
set contains no relays). Similarly, any command accepting naddrs can
reference a set to extract its naddrs.

Sets can also be merged by updating a set while specifying another
set in `--repo` merges their naddrs, while `--set-relays` merges their
relays. Removal follows the same pattern.

Signed-off-by: Awiteb <a@4rs.nl>

src/cli/commands/sets/mod.rs

@@ -0,0 +1,57 @@
+// n34 - A CLI to interact with NIP-34 and other stuff related to codes in nostr
+// Copyright (C) 2025 Awiteb <a@4rs.nl>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://gnu.org/licenses/gpl-3.0.html>.
+
+/// `sets new` command
+mod new;
+/// `sets remove` command
+mod remove;
+/// `sets show` commands
+mod show;
+/// `sets update` command
+mod update;
+
+use clap::Subcommand;
+
+use self::new::NewArgs;
+use self::remove::RemoveArgs;
+use self::show::ShowArgs;
+use self::update::UpdateArgs;
+use super::{CliOptions, CommandRunner};
+use crate::error::N34Result;
+
+#[derive(Subcommand, Debug)]
+pub enum SetsSubcommands {
+    /// Remove a set, or specific repos and relays within it
+    Remove(RemoveArgs),
+    /// Create a new set
+    New(NewArgs),
+    /// Modify an existing set
+    Update(UpdateArgs),
+    /// Show a single set or all the stored sets
+    Show(ShowArgs),
+}
+
+
+impl CommandRunner for SetsSubcommands {
+    async fn run(self, options: CliOptions) -> N34Result<()> {
+        match self {
+            Self::Remove(args) => args.run(options).await,
+            Self::New(args) => args.run(options).await,
+            Self::Update(args) => args.run(options).await,
+            Self::Show(args) => args.run(options).await,
+        }
+    }
+}