feat: add storage module with S3 support and development tooling

Create shared storage module for AWS S3 operations with comprehensive
development infrastructure:

Core Features:
- S3 interface with two upload patterns (manager and direct)
- Presigned URL generation with 15-minute expiration
- Support for multipart uploads and direct PutObject
- Comprehensive test coverage (8 tests, 70.4% coverage)
- Generic implementation without project-specific dependencies

Development Tooling:
- .editorconfig for consistent editor settings
- .pre-commit-config.yaml with Go linters and formatters
- .golangci.yml for golangci-lint configuration
- commitlint.config.js for conventional commit validation
- cliff.toml for automated changelog generation (v0.0.1)
- renovate.json for automated dependency updates
- .gitlab-ci.yml for CI/CD pipeline

CI/CD Pipeline:
- Automated testing with race detection
- Coverage tracking and Codecov integration
- Vulnerability scanning with govulncheck
- Pre-commit validation gates
- Release automation

Module exports:
- New(bucket) - Upload manager pattern for large files
- NewS3(cfg, bucket) - Direct upload pattern
- Store(path, content, contentType) - Upload and get presigned URL

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.pre-commit-config.yaml

@@ -0,0 +1,46 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v6.0.0
+  hooks:
+  - id: trailing-whitespace
+  - id: end-of-file-fixer
+  - id: check-yaml
+    args:
+    - --allow-multiple-documents
+  - id: check-added-large-files
+- repo: https://gitlab.com/devopshq/gitlab-ci-linter
+  rev: v1.0.6
+  hooks:
+  - id: gitlab-ci-linter
+    args:
+    - --project
+    - unboundsoftware/storage
+- repo: https://github.com/alessandrojcm/commitlint-pre-commit-hook
+  rev: v9.23.0
+  hooks:
+  - id: commitlint
+    stages: [ commit-msg ]
+    additional_dependencies: [ '@commitlint/config-conventional' ]
+- repo: https://github.com/dnephin/pre-commit-golang
+  rev: v0.5.1
+  hooks:
+  - id: go-mod-tidy
+  - id: go-imports
+    args:
+    - -local
+    - gitlab.com/unboundsoftware/storage
+- repo: https://github.com/lietu/go-pre-commit
+  rev: v1.0.0
+  hooks:
+  - id: go-test
+  - id: gofumpt
+- repo: https://github.com/golangci/golangci-lint
+  rev: v2.5.0
+  hooks:
+  - id: golangci-lint-full
+- repo: https://github.com/gitleaks/gitleaks
+  rev: v8.28.0
+  hooks:
+  - id: gitleaks