Vitest aliases, fix test file URLs, and add Pointer/RFC6902 tests

[MarcusLongmuir]

Motivation

• Ensure in-repo packages resolve correctly when running Vitest by adding explicit path aliases to the test configs.
• Correct test fixtures that use file URLs so they use a proper file:/// URL form expected by the code.
• Improve coverage for JSON Pointer and RFC6902 patch handling by adding unit tests that exercise arrays, objects, cloning semantics and error cases.

Description

• Added resolve.alias entries to vitest.config.ts in packages/mml-cli and packages/networked-dom-document using node:path to map internal package names to their src/index.ts files for correct module resolution in tests.
• Replaced "file://test.html" with "file:///test.html" across numerous test files to use a canonical file URL form.
• Expanded tests in networked-dom-document including new cases in rfc6902/patch.test.ts (add/remove/replace/move/copy/test/invalid ops) and rfc6902/pointer.test.ts (root pointer, invalid pointers, escaping, prototype poisoning, no-op set, push/add semantics), and updated various e2e and v0.1/v0.2 tests to use the corrected file URL.

Testing

• Ran the repository test suite via Vitest across packages (run via the monorepo test command), including the newly added pointer and RFC6902 tests, and they completed successfully.
• Coverage configuration remains unchanged and continues to produce lcov reports in the coverage directories.

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Codex Task