Add git-based template synchronization for downstream projects

[Copilot]

Downstream projects need to receive template updates (especially dependabot-driven dependency updates) while preserving their git history and project-specific modifications.

Implementation

Core Sync Mechanism (tools/template-sync.py)

• Adds template as git remote, fetches updates, merges via standard 3-way merge
• Dependabot updates flow as regular commits—no special handling required
• Conflict detection with manual resolution workflow
• Dry-run preview mode

Configuration (.templaterc)

• Defines sync/exclude patterns for template vs project-specific files
• Tracks last sync commit for incremental updates

[sync]
exclude_paths = src/*/, tests/test_*.py
sync_paths = .github/workflows/*.yaml, pyproject.toml
smart_merge_files = pyproject.toml, .pre-commit-config.yaml

Documentation

• docs/template-sync.md - Setup, workflow, configuration reference
• docs/template-sync-examples.md - 10 real-world scenarios (conflict resolution, selective sync, emergency updates)
• docs/template-sync-quickstart.md - Command reference

Optional Automation (.github/workflows/template-sync-check.yaml.example)

• Weekly check for template updates
• Creates GitHub issues when updates available

Usage

# In downstream project
python tools/template-sync.py --dry-run  # Preview
python tools/template-sync.py            # Apply merge

# Handles conflicts via standard git workflow
vim conflicted-file && git add && git commit

Design Rationale

Git merge handles dependency updates naturally—when template's pyproject.toml updates pytest 8.2→8.3 via dependabot, downstream projects receive it as a merge commit. Standard 3-way merge preserves both template updates and local modifications. No external dependencies beyond Python stdlib + Git.

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[sonarqubecloud]

Quality Gate failed

Failed conditions
1 Security Hotspot

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