[CI] Skip CI for non-runtime directories and add unittest Claude skill

.claude/skills/write-fastdeploy-unittest/README.md

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+# write-fastdeploy-unittest
+
+A skill that guides AI agents to write CI-compliant unit tests for the FastDeploy project.
+
+## Features
+
+- Automatically selects the appropriate test pattern based on the code under test (pure logic / GPU kernel / offline inference / E2E serving)
+- Follows FastDeploy CI classification rules (multi-GPU sequential vs single-GPU parallel)
+- Meets the 80% diff coverage PR threshold
+- Correctly uses port variables, log isolation, and resource cleanup per CI conventions
+
+## Usage
+
+### Basic — specify a source file
+
+```
+Use the write-fastdeploy-unittest skill to add unit tests for fastdeploy/cache_manager/transfer_factory/file_store/file_store.py
+```
+
+### From coverage report — paste the line directly
+
+```
+Use the write-fastdeploy-unittest skill to add unit tests for:
+
+fastdeploy/model_executor/model_loader/default_loader.py    48  32  14  0  26%  37-38, 42, 46-52, 56-66, 69-97
+```
+
+The coverage report format is: `file_path  Stmts  Miss  Branch  BrMiss  Cover%  Missing_lines`. The agent will focus on the uncovered lines and write tests specifically targeting those branches.
+
+The agent will automatically:
+1. Read the target source file and analyze uncovered lines
+2. Select the appropriate test pattern (Pattern 1-4)
+3. Generate a test file in the corresponding `tests/` subdirectory
+4. Run tests and verify coverage
+
+## Test Pattern Quick Reference
+
+| Pattern | Use Case | Dependencies |
+|---------|----------|--------------|
+| 1 — Pure Logic | config, utils, scheduler, router, etc. | No GPU; mock external deps |
+| 2 — GPU Kernel | ops, layers, numerical computation | Requires GPU; `@pytest.mark.gpu` |
+| 3 — Offline Inference | LLM API, model loading | Requires MODEL_PATH |
+| 4 — E2E Serving | End-to-end HTTP serving | subprocess + ports |
+
+## Key Conventions
+
+- Test file naming: `test_<module>.py`
+- Test class naming: `Test<Module>`
+- Coverage verification: `python -m coverage run --source=<directory> -m pytest <test_file> && coverage report -m`
+- The `--source` parameter must be a directory path, not a dotted module name
+
+## Related Files
+
+- [SKILL.md](SKILL.md) — Full skill instruction document