docs(examples): add metadata filter operator snippets

[moroshani]

Summary

• Add four runnable TypeScript metadata filter examples for $eq, $and, $in, and $near under examples/javascript/metadata-filters/.
• Share setup/query/cleanup logic so each operator snippet stays short and copyable.
• Add npm scripts and README commands for the new examples.

Closes #417

Verification

• npm ci
• npm run type-check
• npm run lint
• git diff --check

Notes

The examples require real MOSS_PROJECT_ID and MOSS_PROJECT_KEY credentials to run end-to-end. I verified them with the local TypeScript and ESLint checks; at runtime they create a temporary index, run one filtered query, and delete the index.

[CLAassistant]

All committers have signed the CLA.

[cubic-dev-ai]

All reported issues were addressed across 7 files

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[moroshani]

Update: I was able to complete the CLA from another device. The CLA check now shows signed. Thanks.

[Copilot]

Pull request overview

Adds runnable, copy-pasteable TypeScript examples demonstrating metadata filter operators in the JavaScript examples package (examples/javascript/), aligning with the repo’s goal of providing practical SDK usage snippets.

Changes:

• Added four runnable operator-focused scripts for $eq, $and, $in, and $near under examples/javascript/metadata-filters/.
• Introduced a shared helper to centralize setup (env, temporary index creation/loading), querying, and teardown.
• Updated the JavaScript examples README and package.json scripts to make running the new samples straightforward.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
examples/javascript/README.md	Documents the new metadata filter operator samples and how to run them.
examples/javascript/package.json	Adds npm run metadata:* scripts to run each operator snippet.
examples/javascript/metadata-filters/shared.ts	Shared runner that creates a temporary index, performs a filtered query, prints results, and cleans up.
examples/javascript/metadata-filters/eq.ts	Runnable $eq filter example.
examples/javascript/metadata-filters/and.ts	Runnable $and composition example.
examples/javascript/metadata-filters/in.ts	Runnable $in filter example.
examples/javascript/metadata-filters/near.ts	Runnable $near geo-distance filter example.

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[github-actions]

Codex review

The examples are structured clearly, but the shared helper currently widens metadata filters enough to break TypeScript checking against the SDK query type.