Modernise Repo

[cabljac]

This is a catch-all PR to do a few things:

• update/fix dependencies
• migrate to nodejs20 runtime on the function, fixing Update node version #27
• fix/unskip tests
• fix Error when using the fileCache option #32 (hopefully, still testing)
• use biome for much quicker linting and formatting

I will break this PR up into smaller atomic ones for easier review, and keep this as a draft for now.

[Copilot]

Pull Request Overview

This PR modernizes the repository by upgrading dependencies, migrating to Node.js 20, replacing TSLint with Biome, and updating function code and tests to use the new runtime and APIs.

• Remove legacy tslint config and switch to Biome for linting/formatting
• Update dependencies and scripts (Node 20 runtime, Firestore/Storage client versions, Jest/Biome configs)
• Refactor Cloud Function imports, storage path logic, and convert tests from axios to native fetch

Reviewed Changes

Copilot reviewed 12 out of 16 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
functions/tslint.json	Removed (replaced by Biome)
functions/tsconfig.json	Dropped Jest types from production build
functions/src/index.ts	Updated imports, storagePath logic, onRequest handler signature
functions/src/build_bundle.ts	Added trailing commas, switched to import type
functions/package.json	Bumped dependencies, switched lint/build/test scripts
functions/jest.config.js	Replaced globals with transform syntax
functions/biome.json	Added Biome configuration
functions/tests/*.test.ts	Converted tests from axios to fetch, unskipped some tests
extension.yaml	Migrated Firebase Function runtime to Node.js 20
_emulator/firebase.json	Added functions emulator port

Comments suppressed due to low confidence (2)

functions/src/index.ts:76

• Consider adding a unit test for storagePath when the query string is empty to verify that no trailing ? is appended.

  const queryString = sortQuery(query);

functions/src/index.ts:54

• [nitpick] The filterQuery function is defined but not currently used; consider removing it or integrating its logic where needed to reduce dead code.

function filterQuery(