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>

internal/config/config.go

@@ -0,0 +1,91 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"gopkg.in/yaml.v3"
+
+	"git.k3nny.fr/releaser/internal/branch"
+)
+
+const filename = ".releaser.yml"
+
+type Config struct {
+	Git    GitConfig    `yaml:"git"`
+	Maven  MavenConfig  `yaml:"maven"`
+	GitLab GitLabConfig `yaml:"gitlab"`
+}
+
+type GitConfig struct {
+	TagPrefix     string `yaml:"tag_prefix"`
+	BranchPattern string `yaml:"branch_pattern"`
+	CommitMessage string `yaml:"commit_message"`
+	AuthorName    string `yaml:"author_name"`
+	AuthorEmail   string `yaml:"author_email"`
+}
+
+type MavenConfig struct {
+	PomPath string `yaml:"pom_path"`
+}
+
+type GitLabConfig struct {
+	URL     string `yaml:"url"`
+	Token   string `yaml:"token"`
+	Project string `yaml:"project"`
+}
+
+func defaults() Config {
+	return Config{
+		Git: GitConfig{
+			TagPrefix:     "v",
+			BranchPattern: branch.DefaultBranchPattern,
+			CommitMessage: "chore(release): {version} [skip ci]",
+		},
+		Maven: MavenConfig{
+			PomPath: "pom.xml",
+		},
+	}
+}
+
+// Load reads .releaser.yml from dir and merges it over the defaults.
+// Missing file is not an error — defaults are returned as-is.
+func Load(dir string) (Config, error) {
+	cfg := defaults()
+
+	data, err := os.ReadFile(filepath.Join(dir, filename))
+	if errors.Is(err, os.ErrNotExist) {
+		return cfg, nil
+	}
+	if err != nil {
+		return cfg, fmt.Errorf("read %s: %w", filename, err)
+	}
+
+	if err := yaml.Unmarshal(data, &cfg); err != nil {
+		return cfg, fmt.Errorf("parse %s: %w", filename, err)
+	}
+
+	return cfg, nil
+}
+
+// ApplyEnv fills empty GitLab fields from the standard GitLab CI environment variables.
+// Values already set in the config file are never overwritten.
+func (c *Config) ApplyEnv() {
+	if c.GitLab.Token == "" {
+		c.GitLab.Token = os.Getenv("GITLAB_TOKEN")
+	}
+	if c.GitLab.URL == "" {
+		// CI_SERVER_URL is the cleanest source ("https://gitlab.example.com")
+		c.GitLab.URL = os.Getenv("CI_SERVER_URL")
+	}
+	if c.GitLab.Project == "" {
+		// Prefer numeric ID; fall back to namespace/project path
+		if id := os.Getenv("CI_PROJECT_ID"); id != "" {
+			c.GitLab.Project = id
+		} else {
+			c.GitLab.Project = os.Getenv("CI_PROJECT_PATH")
+		}
+	}
+}