Task #377: Improve PDF cell spacing, line-height, and use system fontColor

Changes in artifacts/api-server/src/lib/pdf-html-renderer.ts:

1. Increased cell padding from 2px 4px to 10px 12px (body cells) and
   3px 4px to 8px 12px (header cells) for better readability
2. Increased line-height from 1.05 to 1.8 (body cells) and 1.2 to 1.6
   (header cells and body baseline)
3. Page title (h1) now uses system fontColor instead of hardcoded #000
4. Footer text now uses system fontColor for consistency
5. Attendee items get direction-aware margin (12px) for better spacing
6. Logo header uses conditional min-height (55px when logo present,
   auto when absent) to prevent overlap and empty space
7. Footer date-line margin increased from 2px to 4px

Header background (#0B1E3F), header text (white), and border color
(#d1d5db) remain as branded defaults — no DB columns exist for these
yet (follow-up task #378 proposed for that).

No changes to web UI, schema, or legacy pdf-renderer.ts.
Tested: AR and EN PDFs generate successfully with correct sizes.
E2E test passed: login, PDF download (both languages), and UI verified.

artifacts/api-server/src/lib/pdf-html-renderer.ts

@@ -303,15 +303,16 @@ body {
   font-weight: ${fontWeight};
   color: ${fontColor};
   direction: ${dir};
-  line-height: 1.05;
+  line-height: 1.6;
   -webkit-print-color-adjust: exact;
   print-color-adjust: exact;
 }
 
 .page-header {
   text-align: center;
-  margin-bottom: 8px;
+  margin-bottom: 10px;
   position: relative;
+  min-height: ${logoHtml ? "55px" : "auto"};
 }
 
 .page-header .logo {
@@ -323,9 +324,9 @@ body {
 .page-header h1 {
   font-size: ${Math.min(22, fontSize + 6)}px;
   font-weight: bold;
-  color: #000;
+  color: ${fontColor};
   margin: 0;
-  padding: 8px 0;
+  padding: 10px 0;
 }
 
 table {
@@ -345,19 +346,19 @@ thead th {
   color: white;
   font-weight: bold;
   text-align: center;
-  padding: 3px 4px;
+  padding: 8px 12px;
   font-size: ${fontSize}px;
-  line-height: 1.2;
+  line-height: 1.6;
   border: none;
 }
 
 tbody td {
-  padding: 2px 4px;
-  vertical-align: middle;
+  padding: 10px 12px;
+  vertical-align: top;
   text-align: center;
   border: 0.5px solid #d1d5db;
   font-size: ${fontSize}px;
-  line-height: 1.05;
+  line-height: 1.8;
   word-wrap: break-word;
   overflow-wrap: break-word;
 }
@@ -398,12 +399,14 @@ tr {
   white-space: normal;
   direction: ${dir};
   unicode-bidi: isolate;
+  line-height: 1.8;
 }
 
 .attendee-item {
   white-space: nowrap;
   unicode-bidi: isolate;
   display: inline;
+  margin-${isRtl ? "left" : "right"}: 12px;
 }
 
 .page-footer {
@@ -411,6 +414,7 @@ tr {
   bottom: 0;
   ${isRtl ? "right" : "left"}: 0;
   width: 100%;
+  color: ${fontColor};
   font-size: ${Math.max(11, Math.round(fontSize * 0.95))}px;
   text-align: ${isRtl ? "right" : "left"};
   padding-top: 8px;
@@ -421,7 +425,7 @@ tr {
 }
 
 .page-footer .date-line {
-  margin-top: 2px;
+  margin-top: 4px;
 }
 </style>
 </head>