fix(ci): use content-based eslint cache strategy for reliable CI hits (#33327)

## **Description**

Follow-up to #33304 (rolling `.eslintcache` restore/save in CI). That PR
restored the cache correctly, but measured CI job durations showed zero
improvement — `yarn lint` stayed at ~13 minutes on every run, cache or
no cache.

Root cause: ESLint's `--cache` defaults to `--cache-strategy metadata`,
which validates cache entries by file **mtime + size**, not content. CI
does a fresh `actions/checkout` on every run, which gives every file a
brand-new mtime — so every cache entry fails validation and ESLint falls
back to fully re-linting the entire repo, even though the restored cache
was complete and correct.

Verified locally with a controlled reproduction:

| Scenario | `metadata` (default) | `content` |
|---|---|---|
| Warm run, file untouched | 2.0s | — |
| Warm run, after `touch` (new mtime, same content) | **24.1s (full
re-lint)** | **1.8s (cache hit)** |

Switching to `--cache-strategy content` validates by content hash
instead, which survives fresh checkouts — the exact scenario CI cache
restoration produces. This makes the caching added in #33304 actually
effective.

## **Changelog**

CHANGELOG entry: null

## **Related issues**

Fixes:

## **Manual testing steps**

N/A — CI-only configuration change with no in-app behavior to verify.
Validated locally with a controlled cold/warm/touched-mtime comparison
(see description). Follow-up validation: compare `lint` job duration on
this PR's CI run and subsequent `main` runs against the ~13 min baseline
from #33304.

## **Screenshots/Recordings**

### **Before**

N/A

### **After**

N/A

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

#### Performance checks (if applicable)

- [x] I've tested on Android
- [x] I've tested with a power user scenario
- [x] I've instrumented key operations with Sentry traces for production
performance metrics

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

Made with [Cursor](https://cursor.com)

Author: tommasini

package.json

@@ -19,8 +19,8 @@
     "clean": "yarn clean:ios && yarn clean:android && yarn install --immutable",
     "messenger-action-types:generate": "messenger-action-types app --generate",
     "messenger-action-types:check": "messenger-action-types app --check",
-    "lint": "NODE_OPTIONS='--max-old-space-size=12288' eslint '**/*.{js,ts,tsx}' --cache && yarn messenger-action-types:check",
-    "lint:fix": "NODE_OPTIONS='--max-old-space-size=12288' eslint '**/*.{js,ts,tsx}' --fix --cache && yarn messenger-action-types:generate",
+    "lint": "NODE_OPTIONS='--max-old-space-size=12288' eslint '**/*.{js,ts,tsx}' --cache --cache-strategy content && yarn messenger-action-types:check",
+    "lint:fix": "NODE_OPTIONS='--max-old-space-size=12288' eslint '**/*.{js,ts,tsx}' --fix --cache --cache-strategy content && yarn messenger-action-types:generate",
     "lint:clean": "rm -f .eslintcache",
     "lint:tsc": "NODE_OPTIONS='--max-old-space-size=12288' tsc --project ./tsconfig.json",
     "lint:changelog": "./scripts/lint-changelog.sh",