feat: add miden-genesis tool for canonical genesis state

[mmagician]

Summary

• Adds a new miden-genesis binary crate that generates canonical AggLayer genesis accounts and a genesis.toml config file
• Generates three accounts: bridge admin (wallet), GER manager (wallet), and bridge (NoAuth)
• Only the bridge account (nonce=1) is included in genesis.toml for the genesis block; bridge admin and GER manager are local accounts (nonce=0) to be deployed later via transactions
• Supports both default mode (generates Falcon512 keypairs) and custom mode (accepts hex-encoded public keys)

Closes #1788

Operator workflow

# Generate canonical genesis accounts
miden-genesis --output-dir ./genesis

# Bootstrap the node
miden-node validator bootstrap \
  --genesis-block-directory ./data \
  --accounts-directory ./accounts \
  --genesis-config-file ./genesis/genesis.toml \
  --validator.key.hex <key>

Test plan

• cargo build -p miden-genesis compiles
• miden-genesis --output-dir /tmp/genesis-test generates 3 .mac files + genesis.toml
• miden-node validator bootstrap with the generated config produces a valid genesis block
• make lint passes
• cargo nextest run -p miden-node-store - all 118 tests pass

🤖 Generated with Claude Code