Decompose the remaining God Components into hooks, helpers and sub-components

FE6: split the oversized page and panel components into thin layout shells plus colocated use<Component> hooks, .constants.ts, .helpers.ts (with tests) and presentational sub-components, following the established 'logic in a hook, render in slices' pattern. Behaviour, markup, classes and effect order are unchanged. Largest reductions: PackingListPanel 1598->42, FileManager 1055->36, AdminPage 1525->167, BudgetPanel 1266->146, JourneyDetailPage 2822->547, PlacesSidebar 945->66, CollabChat 861->106, CollabNotes 1417->532. DayPlanSidebar's drag-and-drop render body was left intact (ref-identity sensitive) and only its toolbar/modals/constants were extracted.

client/src/components/Collab/CollabChat.constants.ts

@@ -0,0 +1,10 @@
+export const EMOJI_CATEGORIES = {
+  'Smileys': ['😀','😂','🥹','😍','🤩','😎','🥳','😭','🤔','👀','🙈','🫠','😴','🤯','🥺','😤','💀','👻','🫡','🤝'],
+  'Reactions': ['❤️','🔥','👍','👎','👏','🎉','💯','✨','⭐','💪','🙏','😱','😂','💖','💕','🤞','✅','❌','⚡','🏆'],
+  'Travel': ['✈️','🏖️','🗺️','🧳','🏔️','🌅','🌴','🚗','🚂','🛳️','🏨','🍽️','🍕','🍹','📸','🎒','⛱️','🌍','🗼','🎌'],
+}
+
+// Reaction Quick Menu (right-click)
+export const QUICK_REACTIONS = ['❤️', '😂', '👍', '😮', '😢', '🔥', '👏', '🎉']
+
+export const URL_REGEX = /https?:\/\/[^\s<>"']+/g