Add scheduled messages and strip markdown from iMessage responses

Strip markdown formatting (bold, italic, headers, code, links, lists) from
LLM responses before sending via iMessage. Add scheduled messages feature
with CRUD API, background scheduler loop, and admin frontend panel.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

utils/strip_markdown.py

@@ -0,0 +1,35 @@
+import re
+
+
+def strip_markdown(text: str) -> str:
+    """Strip markdown formatting from text for plain-text channels like iMessage."""
+    # Code blocks (fenced)
+    text = re.sub(
+        r"```[\s\S]*?```", lambda m: re.sub(r"```\w*\n?", "", m.group()), text
+    )
+    # Inline code
+    text = re.sub(r"`([^`]+)`", r"\1", text)
+    # Images
+    text = re.sub(r"!\[([^\]]*)\]\([^)]+\)", r"\1", text)
+    # Links — keep the link text
+    text = re.sub(r"\[([^\]]+)\]\([^)]+\)", r"\1", text)
+    # Bold/italic (order matters: bold+italic first)
+    text = re.sub(r"\*\*\*(.+?)\*\*\*", r"\1", text)
+    text = re.sub(r"\*\*(.+?)\*\*", r"\1", text)
+    text = re.sub(r"\*(.+?)\*", r"\1", text)
+    text = re.sub(r"___(.+?)___", r"\1", text)
+    text = re.sub(r"__(.+?)__", r"\1", text)
+    text = re.sub(r"_(.+?)_", r"\1", text)
+    # Headers
+    text = re.sub(r"^#{1,6}\s+", "", text, flags=re.MULTILINE)
+    # Horizontal rules
+    text = re.sub(r"^[-*_]{3,}\s*$", "", text, flags=re.MULTILINE)
+    # Bullet lists — remove the bullet marker
+    text = re.sub(r"^[\s]*[-*+]\s+", "", text, flags=re.MULTILINE)
+    # Numbered lists — remove the number marker
+    text = re.sub(r"^[\s]*\d+\.\s+", "", text, flags=re.MULTILINE)
+    # Blockquotes
+    text = re.sub(r"^>\s?", "", text, flags=re.MULTILINE)
+    # Collapse multiple blank lines
+    text = re.sub(r"\n{3,}", "\n\n", text)
+    return text.strip()