feat(cli, conversation): add conversation fork command (#374)

Introduce the `jp conversation fork` command, allowing users to create a
new conversation based on the contents of an existing one. This is
useful for exploring different paths or isolating specific parts of a
discussion.

The command supports time-based filtering of events using the `--from`
and `--until` flags, which accept both relative (e.g., "5mins") and
absolute timestamps. Users can also immediately switch to the new fork
using the `--activate` flag.

```shell
# Fork the active conversation
jp conversation fork --activate

# Fork a specific conversation with events from 10 minutes ago
jp conversation fork <id> --from 10mins
```

Internally, changes are made to make it easier to test code that relies
on the current timestamp, such as
`Workspace::set_active_conversation_id`, and
`Workspace::create_conversation`. Additionally, the persistence logic
was moved from `Ctx` to `Workspace` to ensure state is saved even when
the workspace is dropped outside of the CLI context.

---------

Signed-off-by: Jean Mertz <[email protected]>

Author: JeanMertz

Cargo.lock

@@ -87,10 +87,12 @@ url = { workspace = true }
 which = { workspace = true, features = ["real-sys"] }
 
 [dev-dependencies]
+assert_matches = { workspace = true }
 indoc = { workspace = true }
 insta = { workspace = true, features = ["toml"] }
 pretty_assertions = { workspace = true, features = ["std"] }
 serial_test = { workspace = true }
+tempfile = { workspace = true }
 test-log = { workspace = true }
 
 [lints]

crates/jp_cli/Cargo.toml

@@ -2,6 +2,7 @@ use super::Output;
 use crate::ctx::Ctx;
 
 mod edit;
+mod fork;
 mod ls;
 mod rm;
 mod show;
@@ -21,6 +22,7 @@ impl Conversation {
             Commands::List(args) => args.run(ctx),
             Commands::Use(args) => args.run(ctx),
             Commands::Edit(args) => args.run(ctx).await,
+            Commands::Fork(args) => args.run(ctx),
         }
     }
 }
@@ -46,4 +48,7 @@ enum Commands {
     /// Edit conversation details.
     #[command(name = "edit")]
     Edit(edit::Edit),
+
+    /// Fork a conversation.
+    Fork(fork::Fork),
 }