Fix Pricing Table / custom properties handling (#7)

* Support custom properties for PricingTable and other LM-specific parameters

Enable passing LM-specific parameters like 'skudef' and 'skus' through a general
custom_properties mechanism. This allows:
- Creating ProductModules with PricingTable model and SKU definitions via skudef
- Creating/updating LicenseTemplates with pricing plan configurations via skus
- Passing any other custom properties as key-value pairs

Updated tools:
- netlicensing_create_product_module: added custom_properties parameter
- netlicensing_update_product_module: added custom_properties parameter
- netlicensing_create_license_template: added custom_properties parameter
- netlicensing_update_license_template: added custom_properties parameter

Updated helper functions:
- product_modules.create_product_module()
- product_modules.update_product_module()
- license_templates.create_license_template()
- license_templates.update_license_template()

Fixes: NetLicensing-MCP refusing to create PricingTable entities due to missing
support for LM-specific parameters.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Clarify include_raw docstrings to refer to the API response

* Ignore local claude config symlink (useful for quick dev testing)

* Add uv.lock

TODO: Review and update README.md and pyproject.toml to ensure the project is fully managed with uv and follows current uv project conventions.

* Enable tests in VSCode

* Extend test coverage

* Address potential custom properties conflicts

* Address misleading wording in docstrings for include_raw

* Improve type-correctness

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Co-authored-by: Claude Haiku 4.5 <noreply@anthropic.com>

Fix GHSA-x9vc-9ffq-p3gj