feat: implement SavePump/SaveAlarms, fix config round-trip bugs, redesign PDF reports

Config system fixes:
- Implement SavePump() — full XML serialization with insert/update by pump ID
- Add CanBusParameter.ToPumpXml() for legacy P1-P6 pump param format
- Fix LastRotationDirection never loaded in LoadSettings()
- Add SaveAlarms() to ConfigurationService and IConfigurationService
- Remove dead fields AppSettings.Clients and AppSettings.PumpIds

PDF report redesign:
- Professional layout with charts, verdict badges, and tolerance bands
- Add ReportChartRenderer (SVG) and ReportTheme styling constants
- Embed default_logo.png as fallback report logo

Documentation:
- Add gap analysis docs (config validation, ford unlock, missing features)
- Update CLAUDE.md architecture, known gaps, and debt tracking

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

Models/CanBusParameter.cs

@@ -225,6 +225,40 @@ namespace HC_APTBS.Models
             return double.Parse(value.Replace(',', '.'), CultureInfo.InvariantCulture);
         }
 
+        /// <summary>
+        /// Serialises this parameter to an XML element using the pump-param format
+        /// (<c>busid</c>, <c>p1–p6</c>, <c>send</c>, <c>disableparams</c>).
+        /// Used when persisting pump definitions to <c>pumps.xml</c>.
+        /// </summary>
+        public XElement ToPumpXml()
+        {
+            var elm = new XElement(Name,
+                new XAttribute("busid", MessageId.ToString("X")),
+                new XAttribute("byteh", ByteH),
+                new XAttribute("bytel", ByteL),
+                new XAttribute("type",  Type));
+
+            if (!IsReceive)
+                elm.Add(new XAttribute("send", "true"));
+            if (Alpha != 1.0)
+                elm.Add(new XAttribute("filter", Alpha.ToString(CultureInfo.InvariantCulture)));
+            if (DisableCalibration)
+            {
+                elm.Add(new XAttribute("disableparams", "true"));
+            }
+            else
+            {
+                elm.Add(new XAttribute("p1", P1.ToString(CultureInfo.InvariantCulture)));
+                elm.Add(new XAttribute("p2", P2.ToString(CultureInfo.InvariantCulture)));
+                elm.Add(new XAttribute("p3", P3.ToString(CultureInfo.InvariantCulture)));
+                elm.Add(new XAttribute("p4", P4.ToString(CultureInfo.InvariantCulture)));
+                elm.Add(new XAttribute("p5", P5.ToString(CultureInfo.InvariantCulture)));
+                elm.Add(new XAttribute("p6", P6.ToString(CultureInfo.InvariantCulture)));
+            }
+
+            return elm;
+        }
+
         /// <summary>Serialises this parameter to an XML element for persistence in bench.xml.</summary>
         public XElement ToXml()
         {