docs: update CHANGELOG.md for v12.2.0 + make generator incremental

Script now reads existing CHANGELOG.md, skips releases already documented,
only fetches bodies for new releases, and prepends them. Pass --full to
force complete regeneration.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -4,6 +4,37 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [12.2.0] - 2026-04-18
+
+## Highlights
+
+**Worktree Adoption** — When a git worktree is merged back into its parent branch, its observations are now consolidated into the parent project's view, so memory follows the code after a merge.
+
+## Features
+
+- **Worktree adoption engine** — consolidates merged-worktree observations under the parent project (#2052)
+- **`npx claude-mem adopt`** — new CLI command with `--dry-run` and `--branch X` flags for manual adoption
+- **Auto-adoption on worker startup** — merged worktrees are adopted automatically when the worker service starts
+- **CWD-based project remap** — project identity derived from `pending_messages.cwd`, applied on worker startup
+- **Parent + worktree read scope** — worktree sessions now include parent repo observations in their read scope
+- **Composite project names** — parent/worktree naming prevents observations from crossing worktrees
+- **Merged-into-parent badge** — UI now flags observations that have been adopted from a merged worktree
+- **Observer-sessions project hidden** — internal bookkeeping project no longer appears in UI lists
+
+## Fixes
+
+- Drop orphan flag when filtering empty-string spawn args (#2049)
+- Self-heal Chroma metadata on re-run
+- Schema guard, startup adoption path, and query parity hardening
+- Git operation timeouts + dry-run sentinel fixes
+- Context derivation uses explicit `projects` array rather than cwd
+
+## Chores
+
+- Removed auto-generated per-directory `CLAUDE.md` files across the tree
+
+**Full Changelog**: https://github.com/thedotmack/claude-mem/compare/v12.1.6...v12.2.0
+
 ## [12.1.6] - 2026-04-16
 
 ## Fix