ui(notifications): €/m² to cent precision, link whole address to Maps

- sqm_price now renders with 2 decimals + German comma separator
  (e.g. "(12,35 €/m²)" instead of "(12 €/m²)").
- Map link covers BOTH address lines, not just the street. Telegram
  Markdown can't span link text across newlines, so each line gets its
  own [text](gmaps_url) — same URL, both lines blue + clickable, layout
  stays two-line.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/notifications.py

@@ -118,7 +118,8 @@ def on_match(user_id: int, flat: dict) -> None:
 
     rent_str = _fmt_num(rent)
     if sqm_price:
-        rent_str += f" ({sqm_price:.0f} €/m²)"
+        # German-style decimal separator, rounded to the cent.
+        rent_str += f" ({sqm_price:.2f} €/m²)".replace(".", ",")
 
     body = (
         f"{line1}\n{line2}\n"
@@ -129,8 +130,14 @@ def on_match(user_id: int, flat: dict) -> None:
         f"Original: {link}\n"
         f"lazyflat: {deep_link}"
     )
+    # Telegram Markdown can't span link text across newlines, so emit two
+    # separate links that share the same Google Maps URL — both lines render
+    # blue + clickable, layout stays two-line.
+    addr_md = f"[{line1}]({gmaps})"
+    if line2:
+        addr_md += f"\n[{line2}]({gmaps})"
     md = (
-        f"[{line1}]({gmaps})\n{line2}\n"
+        f"{addr_md}\n"
         f"Miete: {rent_str}\n"
         f"Fläche: {_fmt_num(size)}\n"
         f"Zimmer: {_fmt_num(rooms)}\n"