Deploy v0.14 counter contract on testnet once testnet upgrades; update counter_contract_increment address

[Keinberger]

Context

counter_contract_increment.rs (and related docs/web-client tutorials) reference a hardcoded counter contract address that was deployed with v0.14 tools on devnet.

AccountId is derived from the code commitment, which uses the Poseidon2 hash function in v0.14. This means:

• v0.13-deployed contract addresses are invalid for v0.14 clients (procedure hash mismatch)
• A v0.14 contract deployed with the same deterministic seed on testnet will produce mtst1XYZ (same suffix as mdev1XYZ)

Required action (when testnet upgrades to v0.14)

1. Run deploy_counter_deterministic.rs with the same seed against testnet RPC
2. Verify the resulting address suffix matches the devnet deployment
3. Update the hardcoded address in rust-client/src/bin/counter_contract_increment.rs to the combined form (following the PR fix: deploy tutorial addresses on both testnet and devnet #177 pattern) so it works on both networks
4. Update the same address in any docs/web-client tutorials that reference it

Note

counter_contract_fpi.rs is not affected — it deploys in-session and requires no hardcoded address.