fix(email): add text/plain part to every transactional + telecom email

All transactional/worker senders built multipart/alternative (or mixed)
messages with ONLY an HTML part. A single-part multipart/alternative is
malformed and HTML-only mail is a spam-score signal -- the same class of
deliverability bug that hurt the campaign pipeline, but on the telecom /
filing / customer-transactional path (499-Q reminders, RMD/FCC filing
review links, intake/completion/delivery emails, commissions, etc).

- worker_email.send_worker_email: auto-derive plaintext from HTML when
  caller omits text= (fixes the shared helper for all current+future use)
- 16 rolled-their-own senders in scripts/workers/** + scripts/formation/
  document_delivery.py: attach html_to_text(...) plaintext sibling before
  the HTML part (job_server + document_delivery wrap text+html in an
  alternative sub-part so PDFs still attach to the mixed root)
- api/src/email.ts: add dependency-free htmlToText() and default
  sendEmail text to it (fixes checkout/webhook HTML-only sends)

Verified: all py files compile + import at runtime, api tsc passes,
htmlToText handles hrefs/lists/entities, 11 plaintext unit tests pass.
Telecom campaign 407 (Jun 8) was HTML-only + sent in the DKIM-broken
window -> 384 sent / 0 clicks (same junked-mail signature).

scripts/workers/services/base_handler.py

@@ -282,6 +282,8 @@ class BaseServiceHandler(ABC):
                 from email.mime.text import MIMEText
                 from email.mime.multipart import MIMEMultipart
 
+                from scripts._email_plaintext import html_to_text
+
                 first_name = customer_name.split(" ")[0] if customer_name else "there"
                 subject = f"Action Required — Complete your {service_label} intake"
                 body = (
@@ -308,6 +310,7 @@ class BaseServiceHandler(ABC):
                     msg["From"] = smtp_from
                     msg["To"] = customer_email
                     msg["Reply-To"] = "info@performancewest.net"
+                    msg.attach(MIMEText(html_to_text(body), "plain"))
                     msg.attach(MIMEText(body, "html"))
                     with smtplib.SMTP(smtp_host, smtp_port) as server:
                         server.starttls()

scripts/workers/services/fcc_carrier_registration.py

@@ -282,6 +282,8 @@ class FCCCarrierRegistrationHandler:
             from email.mime.text import MIMEText
             from email.mime.multipart import MIMEMultipart
 
+            from scripts._email_plaintext import html_to_text
+
             email = order.get("customer_email", "")
             name = order.get("customer_name", "")
             if not email:
@@ -302,6 +304,7 @@ class FCCCarrierRegistrationHandler:
             msg["Subject"] = subject
             msg["From"] = os.environ.get("SMTP_FROM", "Performance West <noreply@performancewest.net>")
             msg["To"] = email
+            msg.attach(MIMEText(html_to_text(body), "plain"))
             msg.attach(MIMEText(body, "html"))
 
             smtp_host = os.environ.get("SMTP_HOST", "co.carrierone.com")

scripts/workers/services/form_499a_discontinuance.py

@@ -241,6 +241,8 @@ class Form499ADiscontinuanceHandler(BaseServiceHandler):
             from email.mime.multipart import MIMEMultipart
             from email.mime.text import MIMEText
 
+            from scripts._email_plaintext import html_to_text
+
             subject = f"Form 499-A Discontinuance Filed — {entity_name}"
             html = f"""
             <div style="font-family:Inter,sans-serif;max-width:600px;margin:0 auto;color:#1f2937">
@@ -275,6 +277,7 @@ class Form499ADiscontinuanceHandler(BaseServiceHandler):
             msg["From"] = os.environ.get("SMTP_FROM", "Performance West <noreply@performancewest.net>")
             msg["To"] = to
             msg["Subject"] = subject
+            msg.attach(MIMEText(html_to_text(html), "plain"))
             msg.attach(MIMEText(html, "html"))
 
             with smtplib.SMTP(

scripts/workers/services/form_499q.py

@@ -338,10 +338,13 @@ class Form499QHandler(BaseServiceHandler):
             from email.mime.multipart import MIMEMultipart
             from email.mime.text import MIMEText
 
+            from scripts._email_plaintext import html_to_text
+
             msg = MIMEMultipart("alternative")
             msg["From"] = os.environ.get("SMTP_FROM", "Performance West <noreply@performancewest.net>")
             msg["To"] = to
             msg["Subject"] = subject
+            msg.attach(MIMEText(html_to_text(html), "plain"))
             msg.attach(MIMEText(html, "html"))
 
             with smtplib.SMTP(

scripts/workers/services/rmd_filing.py

@@ -136,6 +136,8 @@ class RMDFilingHandler(BaseServiceHandler):
                     import smtplib
                     from email.mime.text import MIMEText
                     from email.mime.multipart import MIMEMultipart
+
+                    from scripts._email_plaintext import html_to_text
                     subject = f"Action Required — Review your RMD certification for {entity.get('legal_name', order_number)}"
                     body = (
                         f"<h2>Your RMD Certification is Ready for Review</h2>"
@@ -161,6 +163,7 @@ class RMDFilingHandler(BaseServiceHandler):
                         msg["From"] = smtp_from
                         msg["To"] = customer_email
                         msg["Reply-To"] = "info@performancewest.net"
+                        msg.attach(MIMEText(html_to_text(body), "plain"))
                         msg.attach(MIMEText(body, "html"))
                         with smtplib.SMTP(smtp_host, smtp_port) as server:
                             server.starttls()

scripts/workers/services/telecom/auto_filing.py

@@ -44,6 +44,8 @@ import smtplib
 from dataclasses import dataclass
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
+
+from scripts._email_plaintext import html_to_text
 from typing import Optional
 
 logger = logging.getLogger(__name__)
@@ -279,6 +281,7 @@ def _send_admin_email(
     msg["Subject"] = f"[Review & File] {order_number} — {service_name}"
     msg["From"] = smtp_from
     msg["To"] = to_email
+    msg.attach(MIMEText(html_to_text(html), "plain"))
     msg.attach(MIMEText(html, "html"))
 
     try:

scripts/workers/services/telecom/esign_helper.py

@@ -28,6 +28,8 @@ import smtplib
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 
+from scripts._email_plaintext import html_to_text
+
 logger = logging.getLogger("esign_helper")
 
 
@@ -197,6 +199,7 @@ def _send_signing_email(
     msg["To"] = f"{to_name} <{to_email}>"
     msg["Subject"] = subject
     msg["Reply-To"] = "info@performancewest.net"
+    msg.attach(MIMEText(html_to_text(body), "plain"))
     msg.attach(MIMEText(body, "html"))
 
     with smtplib.SMTP(smtp_host, smtp_port, timeout=30) as server: