docs(changelog): update for v1.9.0

CHANGELOG.md

@@ -1,5 +1,55 @@
 # Changelog
 
+## v1.9.0 — 2026-06-19
+
+### Features
+
+- diff Merge opens the 3-pane editor + conflict overview ruler (29a294b)
+- toggle add/remove per side, MAIN/INCOMING labels, files readout (ca4377e)
+- additive conflict accept — stack ours/theirs in click order (d5eec75)
+- add accept-both control to the 3-pane conflict gutter (18479c0)
+- Rider-style 3-pane conflict editor view (c4d1acc)
+- unify planning conflicts onto the resolver + 3-pane VM foundation (378a92c)
+- move review feedback to the Output tab + review/worktree polish (3e4e4a0)
+- in-app 3-way merge editor (chunk 2b) (92767c6)
+- real conflict-hunk parsing pipeline (chunk 2 backend) (e779e13)
+- My Day actions, orphan-aware grouping, menu restructure (4847c5c)
+- unify review actions into the Git-tab cockpit (43fb506)
+- carry ownerId on sync to prepare for multi-user (cee051b)
+- gate access on Zitadel "user" project role (23c3065)
+- Online Inbox settings tab + auth-code/PKCE login (80a2de6)
+- Online Inbox config + auth hub plumbing (Phase 2) (17c7ff5)
+- real ZitadelAuthProvider (refresh-token grant, auth-code+PKCE) (619bc0c)
+- Online Inbox sync engine (Phase 1) (1ac9ced)
+- let Claude set the cheapest model per generated task via MCP (c27a179)
+
+### Fixes
+
+- unresolved conflicts compose to empty, not Ours (+ review nits) (23a93ce)
+- harden 3-pane editor + document the new conflict resolver (869dd25)
+- invalidate cached access token when the signed-in user changes (cfe23cd)
+- preserve API base path in Online Inbox client (8b347de)
+- queue dispatches skip the StartRunning re-claim (74ca2e0)
+- document and test Queued→Failed guard in FailAsync (fe73f45)
+- stateless AbortPlanningMerge after worker restart mid-merge (fb1d799)
+- route FinalizeParentDoneAsync through TaskStateService (e9e4ad8)
+
+### Refactoring
+
+- bring IWorkerClient to parity with WorkerClient (b5417f6)
+
+### Documentation
+
+- spec + plan for Rider-style 3-pane merge editor (983c177)
+- KunsZitadel is server-side only; desktop uses an OIDC client flow (96da9fb)
+- API contract, desktop design spec, and implementation plan (8cbe1ad)
+- close out the review round in open.md, sync CLAUDE.md with merges (23ff391)
+- record correctness-review findings (4 confirmed as tasks) (ddeded9)
+- record review findings as refactoring backlog (1448794)
+- spec + plan for per-task model override via MCP (51ef488)
+- refresh CLAUDE.md files and open.md to current code state (4904631)
+- update for v1.8.0 (f8f20bf)
+
 ## v1.8.0 — 2026-06-09
 
 ### Features