chore: remove mock price api package and update env configuration (#194)

* chore: remove mock price api package and update env configuration

Removed the mock-price-api package including all its files and updated the environment configuration to use the production price API endpoint instead of the local mock server. Also updated the documentation to reflect the removal of the mock price API setup instructions.

The changes include:
- Removing the mock-price-api package and all its associated files
- Updating the price API base URL in .env.example to point to the production endpoint
- Removing the mock price API related instructions from snapPreinstall.md
- Updating the documentation to reflect the new configuration approach

This change simplifies the setup process by removing the dependency on the local mock price API and standardizes the configuration to use the production price API.

Author: mj-kiwi

docs/snapPreinstall.md

@@ -7,8 +7,7 @@ The tarball will allow us to test preinstall on the public [metamask-extension b
 1. Update the .env `SNAP_ENV=prod` in:
    - `./packages/permissions-kernel-snap/.env`
    - `./packages/gator-permissions-snap/.env`
-2. Set `PRICE_API_BASE_URL=http://localhost:8003` in `./packages/gator-permissions-snap/.env` to fetch spot prices from mock price API running locally.
-3. From root of repo run the following:
+2. From root of repo run the following:
 
 ```bash
 mkdir deps

packages/gator-permissions-snap/.env.example

@@ -4,7 +4,7 @@
 SNAP_ENV=local
 
 # The base URL for the price API used to fetch realtime token spot prices.
-PRICE_API_BASE_URL=http://localhost:8003
+PRICE_API_BASE_URL=https://price.dev-api.cx.metamask.io
 
 # Set `STORE_PERMISSIONS_ENABLED=true` to enable profile sync storage features. This is needed when testing something related to storage otherwise leave `STORE_PERMISSIONS_ENABLED=false`
 STORE_PERMISSIONS_ENABLED=false
@@ -24,4 +24,4 @@ PRICE_API_BASE_URL=https://price.api.cx.metamask.io
 ACCOUNT_API_BASE_URL=https://accounts.api.cx.metamask.io
 TOKENS_API_BASE_URL=https://tokens.api.cx.metamask.io
 KERNEL_SNAP_ID=npm:@metamask/permissions-kernel-snap
-MESSAGE_SIGNING_SNAP_ID=npm:@metamask/message-signing-snap
+MESSAGE_SIGNING_SNAP_ID=npm:@metamask/message-signing-snap