Polish UI: SearchBar sizing, SessionList layout, Tooltip offset, and progress CSS

SearchBar:
- Switch from fixed w-80/sm:w-96 to fluid min-w-80 max-w-md w-full
- Adjust left padding for better visual alignment with search icon

SessionList:
- Memoize project grouping computation with useMemo
- Move horizontal padding from per-item margin (mx-2 + width calc hack)
  to container padding (px-2) for cleaner layout and full-width buttons
- Remove inline width override that was compensating for the old margins

Tooltip:
- Increase offset from 8px to 12px for better visual separation

CSS:
- Add prose-message-progress variant with compact 11px mono typography
  for progress event content (code blocks, tables, links, blockquotes)
- Reduce search minimap marker height from 4px to 3px
- Normalize prose-message line-height: paragraphs 1.625→1.6, list
  items 1.5→1.6 for consistent rhythm
- Switch custom checkbox checkmark sizing from fixed px to percentages
  for better scaling across different zoom levels

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/client/components/SessionList.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useEffect } from "react";
+import React, { useState, useEffect, useMemo } from "react";
 import type { SessionEntry } from "../lib/types";
 
 interface Props {
@@ -11,13 +11,16 @@ interface Props {
 export function SessionList({ sessions, loading, selectedId, onSelect }: Props) {
   const [selectedProject, setSelectedProject] = useState<string | null>(null);
 
-  // Group by project
-  const grouped = new Map<string, SessionEntry[]>();
-  for (const session of sessions) {
-    const group = grouped.get(session.project) || [];
-    group.push(session);
-    grouped.set(session.project, group);
-  }
+  // Group by project (memoized to avoid recomputing on unrelated rerenders)
+  const grouped = useMemo(() => {
+    const map = new Map<string, SessionEntry[]>();
+    for (const session of sessions) {
+      const group = map.get(session.project) || [];
+      group.push(session);
+      map.set(session.project, group);
+    }
+    return map;
+  }, [sessions]);
 
   // Auto-select project when selectedId changes
   useEffect(() => {
@@ -73,7 +76,7 @@ export function SessionList({ sessions, loading, selectedId, onSelect }: Props)
         <div className="px-4 py-2 text-caption font-semibold text-foreground-muted uppercase tracking-wider border-b border-border-muted" style={{ background: "var(--color-surface-inset)" }}>
           {formatProjectName(selectedProject)}
         </div>
-        <div className="py-1">
+        <div className="py-1 px-2">
           {projectSessions.map((session, idx) => {
             const isSelected = selectedId === session.id;
             return (
@@ -81,13 +84,13 @@ export function SessionList({ sessions, loading, selectedId, onSelect }: Props)
                 key={session.id}
                 onClick={() => onSelect(session.id)}
                 className={`
-                  w-full text-left mx-2 my-0.5 px-3 py-2.5 rounded-lg transition-all duration-200
+                  w-full text-left my-0.5 px-3 py-2.5 rounded-lg transition-all duration-200
                   ${isSelected
                     ? "bg-accent-light shadow-glow-accent ring-1 ring-accent/25"
                     : "hover:bg-surface-overlay"
                   }
                 `}
-                style={{ width: "calc(100% - 1rem)", animationDelay: `${idx * 30}ms` }}
+                style={{ animationDelay: `${idx * 30}ms` }}
               >
                 <div className={`text-body font-medium truncate ${isSelected ? "text-accent-dark" : "text-foreground"}`}>
                   {session.summary || session.firstPrompt || "Untitled Session"}
@@ -113,7 +116,7 @@ export function SessionList({ sessions, loading, selectedId, onSelect }: Props)
 
   // Project list
   return (
-    <div className="py-1 animate-fade-in">
+    <div className="py-1 px-2 animate-fade-in">
       {[...grouped.entries()].map(([project, projectSessions]) => {
         const latest = projectSessions.reduce((a, b) =>
           (a.modified || a.created) > (b.modified || b.created) ? a : b
@@ -123,8 +126,7 @@ export function SessionList({ sessions, loading, selectedId, onSelect }: Props)
           <button
             key={project}
             onClick={() => setSelectedProject(project)}
-            className="w-full text-left mx-2 my-0.5 px-3 py-2.5 rounded-lg hover:bg-surface-overlay transition-all duration-200 group"
-            style={{ width: "calc(100% - 1rem)" }}
+            className="w-full text-left my-0.5 px-3 py-2.5 rounded-lg hover:bg-surface-overlay transition-all duration-200 group"
           >
             <div className="flex items-center justify-between">
               <div className="text-body font-medium text-foreground truncate">