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/build-video-list.js

@@ -194,7 +194,7 @@ export default async function ( applist ) {
     // const videosJsonUrl = process.env.VIDEO_SOURCE || `${process.env.VFUNCTIONS_URL}/videos.json`
 
     // Fetch Commits
-    // const response = await axios.get( videosJsonUrl )
+    // const response = await fetch( videosJsonUrl )
     // Extract commit from response data
     const fetchedVideos = await fs.readJson( youtubeVideoPath )//response.data