radicle: Keep pinned repos ordered in config

Do not return them in a random order in radicle-httpd,
so that we can have them in a defined order in
radicle-explorer.

Cargo.lock

@@ -1719,6 +1719,7 @@ checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
 dependencies = [
  "equivalent",
  "hashbrown",
+ "serde",
 ]
 
 [[package]]
@@ -2479,6 +2480,7 @@ dependencies = [
  "fast-glob",
  "fastrand",
  "git2",
+ "indexmap",
  "jsonschema",
  "libc",
  "localtime",

crates/radicle-cli/examples/rad-config.md

@@ -136,7 +136,7 @@ Values for changes are being validated.
 
 ``` (fail)
 $ rad config set web.pinned.repositories 5
-✗ Error: writing configuration to "[..]/.radicle/config.json" failed: validation failure due to invalid type: integer `5`, expected a sequence
+✗ Error: writing configuration to "[..]/.radicle/config.json" failed: validation failure due to invalid type: integer `5`, expected a set
 ```
 
 The type of the operation is validated.

crates/radicle/Cargo.toml

@@ -25,6 +25,7 @@ cyphernet = { workspace = true, features = ["tor", "dns", "p2p-ed25519"] }
 fast-glob = { version = "0.3.2" }
 fastrand = { workspace = true }
 git2 = { workspace = true, features = ["vendored-libgit2"] }
+indexmap = { version = "2", features = ["serde"] }
 libc = { workspace = true }
 localtime = { workspace = true, features = ["serde"] }
 log = { workspace = true, features = ["std"] }

crates/radicle/src/web.rs

@@ -1,6 +1,7 @@
-use crate::prelude::RepoId;
+use indexmap::IndexSet;
 use serde::{Deserialize, Serialize};
-use std::collections::HashSet;
+
+use crate::prelude::RepoId;
 
 /// Web configuration.
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]
@@ -34,5 +35,9 @@ pub struct Config {
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct Pinned {
     /// Pinned repositories.
-    pub repositories: HashSet<RepoId>,
+    #[cfg_attr(
+        feature = "schemars",
+        schemars(with = "std::collections::HashSet<RepoId>")
+    )]
+    pub repositories: IndexSet<RepoId>,
 }