You are a senior Python/FastAPI engineer working in my existing LIA backend. We have already implemented the conversation state machine and logging.

Now I need TWO small clean-up changes to align logging and DB constraints. Please follow these steps EXACTLY and do not change anything else.

────────────────────────────────
GOAL

1) Fix inbound message logging so `dp_messages.sender` is always a logical role ('customer', 'lia', 'manager'), NOT a phone number.
2) Use OPTION A for `dp_messages.mode`: treat `mode` as a free-form classification string. That means:
   - NO strict CHECK constraints on `dp_messages.mode` or `dp_messages.sender` in the database.
   - Values like 'inbound', 'T2_SOFT_NO', 'T3_APPOINTMENT' etc. must be allowed.

You CANNOT run SQL from Replit, but you CAN:
- Update Python code
- Update documentation (replit.md) with SQL I should run in Supabase.

────────────────────────────────
TASK 1 — Fix inbound sender in app/lia_inbound.py

In app/lia_inbound.py you currently have a logging call like this (the exact line numbers may differ):

    await log_inbound_message(
        conn=conn,
        conversation_id=conversation_id,
        channel=channel,
        sender=payload.from_number,
        message_body=payload.body,
        template_key=None,
        mode="inbound",
    )

This causes `dp_messages.sender` to store the phone number, but our design is:

- sender: 'customer' | 'lia' | 'manager'
- channel: 'whatsapp' | 'sms' | etc.
- The phone number is already stored on dp_conversations.from_number / to_number.

✅ Change ONLY this call so that sender is the ROLE, not the phone number:

    await log_inbound_message(
        conn=conn,
        conversation_id=conversation_id,
        channel=channel,
        sender="customer",
        message_body=payload.body,
        template_key=None,
        mode="inbound",
    )

If there are any OTHER inbound logging calls (for the same inbound WhatsApp flow), ensure they also use:

- sender="customer"
- direction is still handled inside log_inbound_message as 'inbound' (do not change that, just the sender parameter).

Do NOT modify the outbound logging, that already uses the correct semantics.

────────────────────────────────
TASK 2 — Option A for dp_messages.mode and sender (no strict CHECK constraints)

We are choosing Option A:

- `dp_messages.mode` should be free-form (whatever last_reply_type / classification we pass in, e.g. 'T2_SOFT_NO', 'T3_APPOINTMENT', 'inbound', etc.)
- `dp_messages.sender` is limited by our code to 'customer', 'lia', 'manager', but we do NOT want a narrow DB CHECK constraint that might conflict with current or future values.

You cannot edit the database directly from Replit, but you MUST:

1) Open replit.md (or the project documentation file you used earlier).
2) Add a short section under a heading like “DB migrations / dp_messages constraints” with the following SQL for me to run manually in Supabase:

   ```sql
   -- Relax dp_messages constraints so mode and sender values can match actual usage

   ALTER TABLE dp_messages DROP CONSTRAINT IF EXISTS dp_messages_mode_chk;
   ALTER TABLE dp_messages DROP CONSTRAINT IF EXISTS dp_messages_sender_chk;