fix: typos in a user-facing success message, comments, and test descriptions

[andromia3]

WHY are these changes introduced?

A handful of typos across the codebase, including one in a user-facing CLI success message. All are 1:1 character fixes; no identifiers, no runtime behaviour, no types touched.

WHAT is this pull request doing?

User-facing CLI output (the one change that actually needs a changeset):

```diff

• outputSuccess('Localhost delivery sucessful')

• outputSuccess('Localhost delivery successful')
  ```
  (`packages/app/src/cli/services/webhook/trigger.ts`) — printed when `shopify app webhook trigger --delivery-method=localhost` succeeds. The matching assertion in `trigger.test.ts` is updated in the same commit.

Code comments:

• `packages/cli-kit/src/public/node/json-schema.ts` — "where the union issue occured" → "occurred".
• `packages/theme/src/cli/utilities/theme-uploader.ts` — "Dependant and independant files are uploaded concurrently" → "Dependent and independent".
• `packages/app/src/cli/services/app/config/link.ts` — "Always use our prefered build options" → "preferred".

Test descriptions (strings passed to `test()`/`describe()`, safe to rename — no identifiers reference them):

• `packages/theme/src/cli/utilities/repl/evaluator.test.ts` — "should add succesful assignments" → "successful".
• `packages/app/src/cli/services/dev/extension/localization.test.ts` — "returns the last succesful locale built" → "successful".
• `packages/cli-kit/src/public/node/context/local.test.ts` — "returns localhost when no cloud enviroment varible exist" had two typos on one line plus a subject-verb agreement slip, now "when no cloud environment variable exists".

How to test your changes?

The only runtime-visible change is the webhook success message. The existing test in `trigger.test.ts` is updated to assert on the corrected string, so the unit test still passes after the fix. Everything else is inside a comment or a test description — no functional impact.

```bash
pnpm --filter @shopify/app test trigger
```

Post-release steps

None.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows) — no platform-specific code touched
• I've considered possible documentation changes — string changes don't affect published docs
• I've considered analytics changes to measure impact — N/A
• The change is user-facing, so I've added a changelog entry with `pnpm changeset add` — patch bump for `@shopify/app` covering the webhook trigger message