Implement lazy imports for numpy and beartype to improve startup time

[yukinarit]

This PR improves serde import time from 200+ msec to 100+ msec.

before

$ python -X importtime -c "import serde" 2>&1 | grep -E "(serde|import time)" | tail -1
import time:       333 |     202650 | serde

after

$ python -X importtime -c "import serde" 2>&1 | grep -E "(serde|import time)" | tail -1
import time:       272 |     104262 | serde

Closes #604

[github-actions]

Please consider formatting your code according to the standards described here: https://github.com/yukinarit/pyserde/blob/main/CONTRIBUTING.md

[github-actions]

Please consider formatting your code according to the standards described here: https://github.com/yukinarit/pyserde/blob/main/CONTRIBUTING.md

[github-actions]

Please consider formatting your code according to the standards described here: https://github.com/yukinarit/pyserde/blob/main/CONTRIBUTING.md

[Copilot]

Pull Request Overview

This PR implements lazy imports for numpy and beartype dependencies to improve serde's startup time from 200+ msec to 100+ msec by deferring module imports until they are actually needed.

• Replaces direct numpy imports with wrapper functions that lazily import numpy functions when called
• Moves beartype and SQLAlchemy imports to be lazy-loaded at usage points
• Adds local imports within functions that need numpy serialization/deserialization functionality

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
serde/se.py	Replaces numpy imports with lazy wrapper functions and adds local imports in render method
serde/de.py	Implements lazy numpy imports with wrapper functions and adds local imports for deserialization
serde/msgpack.py	Moves numpy encode function import to point of usage
serde/json.py	Moves numpy encode function import to point of usage
serde/core.py	Adds blank line after beartype import
serde/compat.py	Implements lazy SQLAlchemy import wrapper function

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[danielgafni]

Just fyi there is this neat TID253 ruff rule you could use to enforce lazy imports for certain dependencies