doc: Add `CHANGELOG.md`

Inspired by other projects, such as Jujutusu, add a `CHANGELOG.md` file
to be updated alongside the actual changes in the heartwood repository.

The file is pre-filled with some release hightlights of earlier releases
from the Radicle home page. The format for the upcoming release is
prepared with the same structure that Jujutsu uses, which is based on
the suggestions at <https://keepachangelog.com>.

See also: https://radicle.zulipchat.com/#narrow/channel/369277-heartwood/topic/Changelog.20in.20tree/with/522524869

CHANGELOG.md

@@ -0,0 +1,113 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## Release Highlights
+
+## Deprecations
+
+## New Features
+
+## Fixed Bugs
+
+## 1.2.0 - 2025-06-02
+
+### Release Highlights
+
+#### Improved Performance of Repository Initialization
+
+There has been a huge improvement in initialising larger repositories. This was, unfortunately, due to `libgit2` being a lot slower than `git` when performing file protocol push and fetches.
+
+#### Better `rad sync` Output
+
+There has been a concerted effort to improve the fetching and announcing output when using `rad sync`. This also helped us improve `rad clone` which should not include many error messages, while also succeeding.
+
+### New Features
+
+#### CLI
+
+- Output JSON lines for `rad cob`
+- Allow showing multiple COBs at once
+- Improvements to help documentation
+- The full set of actions for patches are now available via `rad patch`
+- Better error context when `ssh-agent` connection fails
+- The remote helper will print `git range-diff`s when creating new patch revisions
+- `rad seed` and `rad unseed` can now take multiple RIDs
+- `rad cob [create | update]` have been added
+- `rad config schema` for emitting a JSONSchema of the configuration
+- Better syntax highlighting
+- `rad cob show` handles broken pipes
+- Avoiding obtaining a signer when it is not necessary
+- Print node addresses when syncing
+
+#### Library
+
+- Patch revisions can now be labelled and resolve comments
+- Issues can be listed by status
+- Extend the set of emojis that are supported
+- Provide an API to do a reverse lookup from aliases to NIDs
+- Use `signals_receipts` crate for improved signal handling
+- Integrate more up-to-date Gitoxide crates
+- Ensuring an MSRV of 1.81
+
+## 1.1.0 - 2024-12-05
+
+### Release Highlights
+
+#### Database Migration
+
+This release includes a migration of the COB database to version 2. The
+migration is run automatically when you start your node. If you'd like to run
+it manually, use `rad cob migrate`.
+
+#### CLI
+
+* A new `--edit` flag was added to the `rad id update` command, to make changes
+  to an identity document from your editor.
+* A new `--storage` flag was added to `rad patch cache` and `rad issue cache`
+  that operates on the entire storage, instead of a specific repository.
+* When fetching a repository with `--seed` specified on the CLI, we now try to
+  connect to the seed it if not already connected.
+* A new set of sub-commands were added to `rad config`, for directly modifying
+  the local Radicle configuration. See `rad config --help` for details.
+* Repositories are now initialized with a new refspec for the `rad` remote, that
+  ensures that tags are properly namespaced under their remote.
+* A new `--remote <name>` flag was added to `rad patch checkout` and `rad patch
+  set` to set the remote for those commands. Defaults to `rad`.
+* The `RAD_PASSPHRASE` variable is now correctly treated as no passphrase when
+  empty.
+
+#### Git Remote Helper
+
+* The `GIT_DIR` environment variable is no longer required for listing refs via
+  the remote helper. This means the commands can be run outside of a working
+  copy.
+* Fixed a bug where the wrong commit was used in the Patch COB when merging
+  multiple patches with a single `git push`, resulting in some merged patches
+  showing as unmerged.
+
+#### Collaborative Objects (COBs)
+
+* Fixed compatibility with certain old patches that contained empty reviews.
+* Added a new `review.edit` action to the `xyz.radicle.patch` COB, for editing
+  reviews.
+
+#### Node
+
+* When fetching a repository, the fetch would fail if the canonical branch could
+  not be established. This is no longer the case, allowing the user to handle the problem
+  locally.
+* When fetching a repository, we no longer fail a fetch from a peer that is
+  missing a reference to the default branch.
+* Private RIDs that could sometimes leak over the gossip protocol no longer do.
+  Note that this only affected the identifiers, not any repository data.
+
+#### Protocol
+
+* A new `rad/root` reference is added to the list of signed references
+  (`rad/sigrefs`). This prevents a possible reference grafting attack.