docs: fix EVM account model content for hollow and long-zero accounts

[ayesigaisaac]

PR title

docs: fix EVM account model content for hollow and long-zero accounts

Description

Summary

This PR updates EVM documentation to clarify Hedera account model behavior for hollow accounts and long-zero addresses.

What changed

• Updated evm/differences/accounts-and-keys.mdx

  • Added an explicit explanation of hollow accounts
  • Described how hollow accounts are completed
  • Clarified fallback to EVM Address from Account ID / long-zero form
  • Explained why long-zero addresses are not compatible with ECRECOVER like alias-based EVM addresses
  • Added a link to the faucet flow example

• Updated evm/quickstart/get-test-hbar.mdx

  • Expanded the faucet warning to mention hollow account limitations
  • Added completion guidance for hollow accounts
  • Clarified long-zero fallback behavior
  • Added a link to the EVM account model guide

Why

These docs were missing important account-model details that are critical for EVM developers:

• Understanding the difference between alias-based EVM addresses and long-zero fallback addresses
• Knowing how hollow accounts behave and how to complete them
• Avoiding confusion when ECRECOVER fails due to a long-zero address fallback

Testing

• mint broken-links passed with no broken links found
  @joshmarinacci @akdev @Neurone @kierzniak please recview