Complete Phase 1: parallel sync, IPC, theme colors, lazy CLI loading

- Sync: Parallelize message downloads with asyncio.gather (batch size 5)
- Sync: Increase HTTP semaphore from 2 to 5 concurrent requests
- Sync: Add IPC notifications to sync daemon after sync completes
- Mail: Replace all hardcoded RGB colors with theme variables
- Mail: Remove envelope icon/checkbox gap (padding cleanup)
- Mail: Add IPC listener for refresh notifications from sync
- Calendar: Style current time line with error color and solid line
- Tasks: Fix table not displaying (CSS grid to horizontal layout)
- CLI: Implement lazy command loading for faster startup (~12s to ~0.3s)
- Add PROJECT_PLAN.md with full improvement roadmap
- Add src/utils/ipc.py for Unix socket cross-app communication

src/mail/email_viewer.tcss

@@ -3,7 +3,7 @@
 
 #main_content, .list_view {
   scrollbar-size: 1 1;
-  border: round rgb(117, 106, 129);
+  border: round $border;
   height: 1fr;
 }
 
@@ -43,18 +43,18 @@
 
 #main_content:focus, .list_view:focus {
   border: round $secondary;
-  background: rgb(55, 53, 57);
+  background: $surface;
   border-title-style: bold;
 }
 
 Label#task_prompt {
   padding: 1;
-  color: rgb(128,128,128);
+  color: $text-muted;
 }
 
 Label#task_prompt_label {
   padding: 1;
-  color: rgb(255, 216, 102);
+  color: $warning;
 }
 
 Label#message_label {
@@ -66,7 +66,7 @@ StatusTitle {
   width: 100%;
   height: 1;
   color: $text;
-  background: rgb(64, 62, 65);
+  background: $panel;
   content-align: center middle;
 }
 
@@ -113,8 +113,8 @@ EnvelopeListItem .envelope-row-3 {
 }
 
 EnvelopeListItem .status-icon {
-  width: 3;
-  padding: 0 1 0 0;
+  width: 2;
+  padding: 0;
   color: $text-muted;
 }
 
@@ -124,7 +124,7 @@ EnvelopeListItem .status-icon.unread {
 
 EnvelopeListItem .checkbox {
   width: 2;
-  padding: 0 1 0 0;
+  padding: 0;
 }
 
 EnvelopeListItem .sender-name {
@@ -166,11 +166,11 @@ EnvelopeListItem.selected {
 GroupHeader {
   height: 1;
   width: 1fr;
-  background: rgb(64, 62, 65);
+  background: $panel;
 }
 
 GroupHeader .group-header-label {
-  color: rgb(160, 160, 160);
+  color: $text-muted;
   text-style: bold;
   padding: 0 1;
   width: 1fr;
@@ -222,10 +222,10 @@ GroupHeader .group-header-label {
  
 #envelopes_list {
   ListItem:odd {
-    background: rgb(45, 45, 46);
+    background: $surface;
   }
   ListItem:even {
-    background: rgb(50, 50, 56);
+    background: $surface-darken-1;
   }
   
   & > ListItem {
@@ -269,9 +269,9 @@ GroupHeader .group-header-label {
 }
 
 Label.group_header {
-  color: rgb(140, 140, 140);
+  color: $text-muted;
   text-style: bold;
-  background: rgb(64, 62, 65);
+  background: $panel;
   width: 100%;
   padding: 0 1;
 }
@@ -300,6 +300,3 @@ ContentContainer {
   width: 100%;
   height: 1fr;
 }
-.checkbox {
-  padding-right: 1;
-}