Add TigrblApp/TigrblApi mount_openrpc & mount_lens methods and simplify mount_openrpc signature

[cobycloud]

Motivation

• Provide a simpler functional API for mounting the OpenRPC spec so callers can pass only the app/api instance and omit the router argument.
• Offer convenience instance methods on both TigrblApp and TigrblApi for mounting OpenRPC and Lens endpoints to improve ergonomics and parity with mount_jsonrpc.
• Update integration tests to cover the new usage patterns and ensure both functional and bound forms behave identically.

Description

• Changed mount_openrpc in tigrbl/system/docs/openrpc.py to accept router: Any | None = None and to default the target router to the provided api when router is not supplied, returning the target router.
• Added mount_openrpc(...) and mount_lens(...) instance methods to TigrblApp (tigrbl/app/tigrbl_app.py) that delegate to the module-level mount functions.
• Added the same mount_openrpc(...) and mount_lens(...) instance methods to TigrblApi (tigrbl/api/tigrbl_api.py) that delegate to the module-level mount functions.
• Updated integration tests in tigrbl_tests to use the simplified functional API (mount_openrpc(app, path=...)) and added new tests exercising the bound instance methods for both TigrblApp and TigrblApi for mount_openrpc and mount_lens.

Testing

• Ran formatting and linting for the changed packages with uv run --directory standards --package tigrbl ruff format . and uv run --directory standards --package tigrbl ruff check . --fix, and for the tests package with uv run --directory standards --package tigrbl-tests ruff format . and uv run --directory standards --package tigrbl-tests ruff check . --fix; all checks passed.
• Executed the updated integration tests directly with uv run --package tigrbl-tests --directory standards pytest tigrbl_tests/tests/i9n/test_mountable_openrpc_uvicorn.py tigrbl_tests/tests/i9n/test_mountable_lens_uvicorn.py and they passed.
• Ran the full tigrbl_tests suite with uv run --package tigrbl-tests --directory standards pytest tigrbl_tests/tests and observed successful results: 934 passed, 14 skipped, 4 xfailed.

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