fix: implement Phase 2 medium-impact spacing reductions

Applied systematic spacing optimizations across admin manager components (40px savings):

DatabaseManager.tsx:
- Input field padding: py-3 → py-2 (3 inputs: retention_count, schedule_hour, schedule_freq_days)
- Form field spacing: space-y-2 → space-y-1.5 (Max Backups field group)
- Grid gaps: gap-4 → gap-3 (storage policy fields)
- Item list spacing: space-y-2 → space-y-1.5 (backup list)
- Modal form spacing: space-y-4 → space-y-3 (recovery points section)
- Backup metadata text: text-[11px] → text-xs (created_at + filesize display)

LdapManager.tsx:
- Input field padding: py-2.5 → py-2 (4 inputs: server_uri, base_dn, user_template, groups_dn)
- Form field spacing: space-y-1.5 → space-y-1 (all label+input groups)
- Button padding: py-2.5 → py-2 (test connection), py-3 → py-2.5 (save policy)

IdentityManager.tsx:
- Input field padding: py-3 → py-2 (username, password, role in edit modal)
- Form field spacing: space-y-4 → space-y-3 (edit modal form)
- Form field labels: space-y-1.5 → space-y-1 (all 3 fields)
- User list spacing: space-y-2 → space-y-1.5 (user items)

AiManager.tsx:
- Grid gaps: gap-4 → gap-3 (provider options grid)
- Input field padding: py-3 → py-2 (Gemini/Claude API key inputs)
- Form field spacing: space-y-2 → space-y-1.5 (API key field groups)
- Modal spacing: space-y-6 → space-y-3 (provider access keys section)
- Prompt section spacing: space-y-4 → space-y-3 (system prompt area)

CategoryManager.tsx:
- Grid gaps: gap-3 → gap-2.5 (category items grid)
- Input field padding: py-3.5 → py-2.5, py-4 → py-2.5 (name + description inputs)
- Form field spacing: space-y-6 → space-y-3, space-y-1.5 → space-y-1 (edit modal)

Test Results:
- Frontend (Vitest): 291/291 tests passing ✓
- Backend (Pytest): 41/41 tests passing ✓
- Total: 332 tests validated, zero regressions

All changes maintain visual hierarchy and premium density standards without sacrificing usability.

.claude/settings.local.json

@@ -72,7 +72,8 @@
       "Bash(git pull *)",
       "Bash(git rm *)",
       "Bash(git merge *)",
-      "Bash(git tag *)"
+      "Bash(git tag *)",
+      "mcp__gemini-cli__ask-gemini"
     ]
   }
 }