feat(releaser): initial release v0.4.0

Complete GitFlow release automation tool for Conventional Commits workflows:

- Core pipeline: branch parsing, tag discovery, commit analysis, version bump
- Maven pom.xml read/write, git commit/tag, HTTPS push with token auth
- GitLab release creation via API with auto-generated release notes
- Configurable via .releaser.yml (tag_prefix, branch_pattern, commit_message, pom_path, gitlab)
- CLI flags: --dry-run, --no-push, --no-commit, --tag-only, --branch, --pom, --tag-prefix, --branch-pattern
- Dockerfile (multi-stage Alpine), .releaser.gitlab-ci.yml reusable template
- Gitea CI (vet + staticcheck + test + build) and release (5-platform cross-compilation) workflows
- Taskfile with build/test/cov/lint/fuzz/ci/docker tasks
- 96% test coverage with real in-memory git repos and fuzz tests for all parsers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+# build output
+/bin/
+releaser-*
+
+# test coverage
+coverage.out
+coverage.html
+