fix(reminders): sanitize ntfy Title header to ASCII (#5208)

* fix(reminders): sanitize ntfy Title header to ASCII

The ntfy notification Title header was set directly from the note title.
HTTP headers must be ASCII, so a title containing emoji or other
non-ASCII characters caused httpx to raise UnicodeEncodeError, which
was swallowed by the surrounding try/except — so the reminder silently
failed and no notification was ever sent.

Sanitize the title with encode('ascii', 'replace') before placing it
into the header, replacing unsupported characters with '?'. This is
standard practice for HTTP header values. The note body is unaffected
(it is sent as request content, not a header) and continues to support
full UTF-8.

* fix(reminders): also truncate ntfy title to 200 chars for header safety

* style: compact ntfy header comment

---------

Co-authored-by: Am-GJ <Am-GJ@users.noreply.github.com>
Co-authored-by: RaresKeY <158580472+RaresKeY@users.noreply.github.com>

ROADMAP.md

@@ -12,7 +12,6 @@ the codebase, you are probably right to stay away.
   and WSL all need coverage.
 
 - Integration audit: do integrations even work? Confirm what works, what needs setup docs, and what should be removed or hidden. 
-- Self-host troubleshooting cookbook. Document the weird 30-second fixes that otherwise become 30-minute searches: Dovecot cleartext auth for local stacks, ntfy Android Instant Delivery for non-ntfy.sh servers, clipboard limits on plain-HTTP Tailscale URLs, Radicale collection URLs, and similar traps.
 - Cookbook reliability on other computers. This is probably the area most likely to need work across different machines, GPUs, drivers, shells, and Python environments.
 - Cookbook SGLang support across platforms. Make sure SGLang setup/serve works
   predictably on Linux, Windows/WSL, macOS where possible, Docker, and common

routes/note_routes.py

@@ -479,7 +479,9 @@ async def dispatch_reminder(
                 base = intg["base_url"].rstrip("/")
                 topic = settings.get("reminder_ntfy_topic") or "reminders"
                 ntfy_body = synthesis or note_body or title
-                hdrs = {"Title": title or "Reminder", "Priority": "high", "Tags": "bell"}
+                # ntfy Title is an ASCII HTTP header; sanitize Unicode and cap its length.
+                _clean_title = (title or "Reminder").encode("ascii", "replace").decode("ascii")[:200]
+                hdrs = {"Title": _clean_title, "Priority": "high", "Tags": "bell"}
                 api_key = intg.get("api_key", "")
                 if api_key:
                     hdrs["Authorization"] = f"Bearer {api_key}"