Send SMS with Python

Add SMS sending to this Python project with TextKit.

- Docs for this stack: https://jointextkit.com/docs/send-with-python.md
- API: POST https://api.jointextkit.com/v1/messages with `Authorization: Bearer
  <key>` and a JSON body `{"to": "+1...", "body": "..."}`.
- Use the official SDK: `pip install jointextkit`, then
  `TextKit().messages.send(to=..., body=...)`.
- Read the key from the `TEXTKIT_API_KEY` environment variable. Never hardcode
  it or send it to the browser.
- Phone numbers are E.164 and US or Canada only (`+1` followed by 10 digits).
- A test key (`ssms_sk_test_`) simulates: `+15005550006` always ends `delivered`
  and no phone gets a text.
- Errors are JSON: `{"error": {"code", "message", "param"}}` with a 4xx status.
  On `429`, wait `Retry-After` seconds and retry.
- Send only from server code that runs after a real event (a signup, an order).
  Never expose an endpoint that texts any number a visitor types.

export TEXTKIT_API_KEY=ssms_sk_test_...

pip install jointextkit

from jointextkit import TextKit

client = TextKit()  # reads TEXTKIT_API_KEY

message = client.messages.send(
    to="+15005550006",
    body="Hello from TextKit",
)

print(message["id"], message["status"])

python send.py

from jointextkit import TextKit, TextKitError

client = TextKit()

try:
    client.messages.send(to="+15005550006", body="Hello from TextKit")
except TextKitError as err:
    # err.code: "invalid_request", "rate_limited", ...  err.status: the HTTP status
    print(err.status, err.code, err)