feat: Add automatic semantic versioning workflow

- Create GitHub Actions workflow for automatic version bumping based on PR title prefixes
- Add version bumping script (scripts/bump_version.py) for programmatic updates
- Update PR template with semantic versioning guidelines
- Document versioning workflow in contributing guide
- Integrate with existing Docker build workflow via git tags

This enables automatic version management:
- feat: triggers MINOR version bump
- fix: triggers PATCH version bump
- breaking: triggers MAJOR version bump
- docs/chore/test: no version bump

🤖 Generated with Claude Code

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

scripts/README.md

@@ -0,0 +1,44 @@
+# Scripts Directory
+
+This directory contains utility scripts for the Gemini MCP Server project.
+
+## bump_version.py
+
+A utility script for semantic version bumping that integrates with the automatic versioning workflow.
+
+### Usage
+
+```bash
+python scripts/bump_version.py <major|minor|patch>
+```
+
+### Examples
+
+```bash
+# Bump patch version (e.g., 3.2.0 → 3.2.1)
+python scripts/bump_version.py patch
+
+# Bump minor version (e.g., 3.2.0 → 3.3.0)
+python scripts/bump_version.py minor
+
+# Bump major version (e.g., 3.2.0 → 4.0.0)
+python scripts/bump_version.py major
+```
+
+### Features
+
+- Reads current version from `config.py`
+- Applies semantic versioning rules
+- Updates both `__version__` and `__updated__` fields
+- Preserves file formatting and structure
+- Outputs new version for GitHub Actions integration
+
+### Integration
+
+This script is primarily used by the GitHub Actions workflow (`.github/workflows/auto-version.yml`) for automatic version bumping based on PR title prefixes. Manual usage is available for special cases.
+
+### Version Bump Rules
+
+- **Major**: Increments first digit, resets others (3.2.1 → 4.0.0)
+- **Minor**: Increments second digit, resets patch (3.2.1 → 3.3.0)
+- **Patch**: Increments third digit (3.2.1 → 3.2.2)