docs: Use bech32 for AccountID across all docs and CLI output

## Context

From [devrel#126 feedback](https://github.com/0xMiden/miden-devrel/issues/126#issuecomment-3933628618) by @Dominik1999.

## Problem

AccountIDs are displayed in hex format throughout docs and CLI output. Should use bech32 representation everywhere for consistency and usability.

## Affected pages

- Quick Start CLI Basics (wallet output)
- Your First Smart Contract (deploy script output)
- All code examples that print AccountIDs

Also needs a corresponding issue in the client repo for CLI output changes.