Finish axios migration via shared native HTTP helper

Replace all in-scope axios callsites with a new helpers/http.js wrapper over native fetch, including JSON/text GET, JSON POST, HEAD checks, and transient 5xx retry behavior; update all browser, build, script, and proxy API clients to use it; add focused unit tests; and remove axios from package dependencies.

Constraint: Preserve API/build and deployment behavior while lowering transport surface area.

Rejected: inline fetch replacements at each callsite | rejected to avoid inconsistent error/retry semantics.

Confidence: high

Scope-risk: moderate

Directive: Keep helper in place as the transport boundary and update tests when changing request semantics.

Tested: pnpm run -s typecheck, pnpm -s run test-prebuild, pnpm -s run test, pnpm -s run test:browser, pnpm -s run netlify-build, smoke GETs on /apple-silicon-app-test and /apple-silicon-app-test/?version=2

Not-tested: branch/netlify deployment health in CI pipeline after merge

helpers/api/youtube/build.js

@@ -1,8 +1,8 @@
 import fs from 'fs-extra'
 import { google } from 'googleapis'
-import axios from 'axios'
 
 import { playlists, benchmarksPlaylistId } from './playlists.js'
+import { getJson } from '~/helpers/http.js'
 
 
 export const youtubeVideoPath = './static/api/youtube-videos.json'
@@ -167,8 +167,7 @@ export async function saveYouTubeVideos () {
     // const youtubeVideos = await getYouTubeVideos()
 
     // Locked previously sucessful YouTube API data for now
-    const youtubeVideos = await axios( process.env.VIDEO_SOURCE )
-        .then( response => response.data )
+    const youtubeVideos = await getJson( process.env.VIDEO_SOURCE )
 
 
     // Save to JSON