v0.35.0

Syncs the Elixir port to Python guava-sdk 0.35.0.

Wire protocol

• New send-agent-dtmf command (Guava.Call.send_dtmf/2); removed the deleted reconnect-outbound command.
• RegisteredHooks gains accept_dtmf_for_numbers; Field/SerializableField gain sensitive; DTMFPressed gains recent_digits.
• Removed the deleted socket-health event.
• Field types: added digit_sequence and cvv; dropped datetime.

New public API

• Guava.Call.send_dtmf/2 — press a DTMF sequence (PSTN/SIP only).
• handle_validate/4 — field validators that auto-retry a task on failure.
• accept_dtmf option on use Guava.Agent.

Not ported (intentional)

• Edge/wakeword features and the optional health server — see PARITY.md.

Housekeeping

• Wire fixtures regenerated from guava-sdk 0.35.0; behaviour tests added; version markers bumped to 0.35.0.

Install:
```elixir
{:guava, "~> 0.35"}
```