feat(astrolabe): add Nextcloud App Store deployment automation

Add complete CI/CD pipeline for automated Astrolabe app releases:
- GitHub Actions workflow for build, sign, and publish
- Makefile for app store package creation
- Version synchronization between info.xml and package.json
- CHANGELOG.md with v0.1.0 release notes

feat: configure commitizen monorepo with independent versioning

Enable independent versioning for three components using scope-based commits:
- MCP Server (feat(mcp) or unscoped): v* tags, updates pyproject.toml + Chart.yaml:appVersion
- Helm Chart (feat(helm)): nextcloud-mcp-server-* tags, updates Chart.yaml:version
- Astrolabe App (feat(astrolabe)): astrolabe-v* tags, updates info.xml + package.json

Changes:
- Add .cz.toml configs for Astrolabe and Helm chart
- Update root pyproject.toml with scope filtering and tag ignores
- Create bump helper scripts (bump-mcp.sh, bump-helm.sh, bump-astrolabe.sh)
- Add CONTRIBUTING.md with version management documentation
- Create component-specific changelogs
- Configure appVersion/version separation for Helm chart

This allows each component to release independently while maintaining
proper version tracking and changelog generation.

CHANGELOG.md

@@ -1,3 +1,10 @@
+# Changelog - MCP Server
+
+All notable changes to the Nextcloud MCP Server will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [PEP 440](https://peps.python.org/pep-0440/).
+
 ## v0.53.0 (2025-12-19)
 
 ### Feat