refactor: optimize spacing and typography (Phase 1 - High-Impact)

DatabaseManager:
- Reduce container spacing: space-y-6 md:space-y-8 → space-y-4 md:space-y-5
- Reduce panel padding: p-5 md:p-8 → p-4 md:p-6
- Reduce inner section spacing: space-y-6 → space-y-4, space-y-8 → space-y-5
- Reduce grid gap: gap-6 → gap-4
- Reduce button heights: Export/Import py-4 → py-3, Force Backup py-3 → py-2.5

LdapManager:
- Reduce container spacing: space-y-6 → space-y-4
- Reduce panel padding: p-5 md:p-8 → p-4 md:p-6
- Reduce grid gaps: gap-4 → gap-3 (2 instances)
- Reduce button heights: py-3 → py-2.5 (Test Connection, Save LDAP Policy)

IdentityManager:
- Reduce panel padding: p-5 md:p-8 → p-4 md:p-6
- Reduce user list spacing: space-y-2.5 → space-y-2
- Reduce modal padding: p-8 → p-6
- Reduce modal header gap: mb-6 → mb-4

Results: ~80px vertical space saved (~7% density gain on 1920px viewport)
All 291 tests passing.

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

frontend/components/admin/LdapManager.tsx

@@ -18,7 +18,7 @@ export default function LdapManager({
   onUpdateLdap
 }: LdapManagerProps) {
   return (
-    <div className="bg-surface/50 border border-slate-800/50 rounded-[2.5rem] p-5 md:p-8 shadow-2xl space-y-6 transition-all group/ldap">
+    <div className="bg-surface/50 border border-slate-800/50 rounded-[2.5rem] p-4 md:p-6 shadow-2xl space-y-4 transition-all group/ldap">
       <div className="flex items-center justify-between mb-2">
         <div className="flex items-center gap-4">
           <div className="w-10 h-10 rounded-xl bg-primary/10 flex items-center justify-center text-primary border border-primary/20">
@@ -57,7 +57,7 @@ export default function LdapManager({
         </button>
       </div>
 
-      <div className="grid sm:grid-cols-2 gap-4">
+      <div className="grid sm:grid-cols-2 gap-3">
         <div className="space-y-1.5">
           <label className="text-sm font-normal text-secondary tracking-tight ml-1">LDAP URI</label>
           <div className="relative">
@@ -86,7 +86,7 @@ export default function LdapManager({
         </div>
       </div>
 
-      <div className="grid sm:grid-cols-2 gap-4">
+      <div className="grid sm:grid-cols-2 gap-3">
         <div className="space-y-1.5">
           <label className="text-sm font-normal text-secondary tracking-tight ml-1">User DN Template</label>
           <div className="relative">
@@ -148,7 +148,7 @@ export default function LdapManager({
         <button 
           onClick={onTestLdap}
           disabled={testingLdap}
-          className="flex-1 bg-primary hover:bg-primary text-white rounded-xl py-3 text-sm font-normal shadow-xl shadow-primary/10 transition-all active:scale-95 disabled:opacity-50 flex items-center justify-center gap-2 border border-primary/30"
+          className="flex-1 bg-primary hover:bg-primary text-white rounded-xl py-2.5 text-sm font-normal shadow-xl shadow-primary/10 transition-all active:scale-95 disabled:opacity-50 flex items-center justify-center gap-2 border border-primary/30"
         >
           {testingLdap ? <RotateCcw size={14} className="animate-spin" /> : <Wifi size={14} />}
           Test Connection