Sync latest discount function examples

[devisscher]

Problem

discounts-reference-app has drifted from the examples and reference material in discount-functions-testing. The accumulated source changes include updated Function APIs and tooling, app intent links for create and edit flows, and refreshed JavaScript and Rust examples.

A first regeneration also exposed two source defects that would have removed live Rust tutorial coderefs and left the generated React Router lint command unusable. Those fixes are tracked in discount-functions-testing#1438.

What this PR does

• Regenerates the full reference app from DFT main at 5cd46c55, plus the source fixes in Shopify/discount-functions-testing#1438 at 8505d6cd.
• Updates generated API types, dependencies, Function sources, Rust targets, and React Router scaffolding.
• Adds the JavaScript and Rust app intent schemas, instructions, and admin.app.intent.link examples for discount create and edit flows.
• Preserves every existing coderef tag and adds paired discount-function.app-intent-link coderefs for JavaScript and Rust.
• Includes the generated app-intent content from Add shopify/Discount app intent link snippets for React Router tutorial #75, so that focused PR is no longer needed once this PR lands.

This is generated output. Source changes belong in discount-functions-testing; this PR does not curate the generated files by hand.

Test plan

Reproduce validation

Prerequisites:

• Node.js 22.22 or later and pnpm 10.33
• Rust with the wasm32-unknown-unknown target
• Shopify CLI 4.5 or later for JavaScript Function builds
• A valid local shopify.app.toml when running Shopify CLI builds

1. Install dependencies:

   pnpm install -r

2. Validate the React Router app:

   cd examples/react-router-app
   env -u HOST -u PORT -u SHOPIFY_APP_URL pnpm lint
   env -u HOST -u PORT -u SHOPIFY_APP_URL pnpm build

   Expected: lint exits 0 with no errors, and client and SSR bundles build.

3. Validate the mock HTTP server:

   cd examples/mock-http-server
   pnpm build

   Expected: client and SSR bundles build.

4. Run the JavaScript unit tests:

   cd examples/javascript/default/extensions/discount-function
   ./node_modules/.bin/vitest run src/

   Expected: 7 tests pass across 2 files. The other three JavaScript examples currently contain no unit-test files.

5. Build each JavaScript Function from a temporary app directory containing a valid shopify.app.toml:

   shopify app function build --path extensions/discount-function

   Repeat for default, network-access, metafield, and discount-rejection.

   Expected: each command produces dist/function.wasm.

6. Test and build each Rust Function:

   for example in default network-access metafield discount-rejection; do
     (
       cd "examples/rust/$example/extensions/discount-function"
       cargo test
       cargo build --release --target wasm32-unknown-unknown
     )
   done

   Expected: all four test commands and all four WASM builds pass.

7. Verify generated documentation contracts:

   • Parse all JSON files with a JSON parser.
   • Parse all TOML files with a TOML parser.
   • Compare [START ...] and [END ...] tag inventories against main.

   Expected: all files parse, every tag is balanced, and no coderef tag is removed.

Local development results

Validated on 2026-08-05 at reference-app commit e99fb28 using DFT source commit 8505d6cd, Node.js 22.22.0, pnpm 10.33.0, and Shopify CLI 4.5.1.

• Full reference-app generation passed. Repeating generation from the same source left the committed worktree clean.
• Documentation contract review passed: 618 JSON files and 29 TOML files parsed; all coderefs were balanced; no existing coderef tags were removed.
• React Router lint passed with 0 errors and 16 existing no-explicit-any warnings.
• React Router client and SSR builds passed.
• Mock HTTP server client and SSR builds passed.
• All four JavaScript Functions built successfully. The default example's 7 tests passed; the other examples contain no test files.
• All four Rust cargo test commands passed, with 6 total tests, and all four wasm32-unknown-unknown release builds passed.
• No merchant-shop or end-to-end app-intent flow was run for this generated sync. The app-intent files match the focused implementation in Add shopify/Discount app intent link snippets for React Router tutorial #75 byte-for-byte.