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/new.rs

@@ -0,0 +1,59 @@
+// 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>.
+
+use clap::Args;
+
+use crate::{
+    cli::{
+        CliConfig,
+        CliOptions,
+        ConfigError,
+        MutRepoRelaySetsExt,
+        traits::CommandRunner,
+        types::{NaddrOrSet, NaddrOrSetVecExt, RelayOrSet, RelayOrSetVecExt},
+    },
+    error::N34Result,
+};
+
+#[derive(Args, Debug)]
+pub struct NewArgs {
+    /// Unique name for the set
+    name:   String,
+    /// Optional relay to add it to the set, either as URL or set name to
+    /// extract its relays. [aliases: `--sr`]
+    #[arg(long = "set-relay", alias("sr"))]
+    relays: Vec<RelayOrSet>,
+    /// Repository address in `naddr` format (`naddr1...`), NIP-05 format
+    /// (`4rs.nl/n34` or `_@4rs.nl/n34`), or a set name like `kernel`.
+    #[arg(value_name = "NADDR-NIP05-OR-SET", long = "repo")]
+    naddrs: Vec<NaddrOrSet>,
+}
+
+impl CommandRunner for NewArgs {
+    // FIXME: The signer is not required here
+    async fn run(self, options: CliOptions) -> N34Result<()> {
+        let mut config = CliConfig::load_toml(&options.config_path)?;
+        let naddrs = self.naddrs.flat_naddrs(&config.sets)?;
+        let relays = self.relays.flat_relays(&config.sets)?;
+
+        if relays.is_empty() && naddrs.is_empty() {
+            return Err(ConfigError::NewEmptySet.into());
+        }
+
+        config.sets.push_set(self.name, naddrs, relays)?;
+        config.dump_toml(&options.config_path)
+    }
+}