docs: add copyright year update step to implement, test, and refactor skill checklists

Co-authored-by: afranken <763000+afranken@users.noreply.github.com>

Author: Copilot

.claude/skills/implement/SKILL.md

@@ -32,6 +32,7 @@ Follow **DTO → Store → Service → Controller** (see AGENTS.md Architecture)
 - [ ] Read root + module `AGENTS.md` (required before any other step)
 - [ ] Identify the S3 API operation ([AWS docs](https://docs.aws.amazon.com/AmazonS3/latest/API/Welcome.html))
 - [ ] Review existing similar implementations
+- [ ] **Update the copyright year** to the current year in the license header of every file you modify
 - [ ] Run `make format` then `make install`
 - [ ] Invoke the **`test` skill** to add/update unit and integration tests
 - [ ] Invoke the **`document` skill** to update `CHANGELOG.md`, `README.md`, and `AGENTS.md`

.claude/skills/refactor/SKILL.md

@@ -35,6 +35,7 @@ Document what, why, and gotchas. Link to AWS API docs where relevant. See **[doc
 
 - [ ] Verify no behavior changes — run tests
 - [ ] Run `make format`
+- [ ] **Update the copyright year** to the current year in the license header of every file you modify
 - [ ] Ensure comments explain *why*, not *what*
 - [ ] Add KDoc for all public APIs
 - [ ] Use self-documenting names

.claude/skills/test/SKILL.md

@@ -20,6 +20,7 @@ Read **[docs/TESTING.md](../../../docs/TESTING.md)**, **[docs/KOTLIN.md](../../.
 
 - [ ] Read `docs/TESTING.md` and root + module `AGENTS.md`
 - [ ] If existing tests have structural problems (poor naming, shared state, weak assertions), invoke the **`refactor` skill** to fix them rather than working around them
+- [ ] **Update the copyright year** to the current year in the license header of every file you modify
 - [ ] Verify tests pass locally
 - [ ] Cover both success and failure cases
 - [ ] Keep tests independent (no shared state, UUID bucket names)