perf: cache filtered collections and add equatable row views

Convert filteredJobs, filteredPastes, and filteredTickets from computed
properties to stored properties updated via didSet on their inputs. Each
update function guards with an equality check before assigning, so
@Observable skips the notification when the filtered result hasn't
changed — preventing list re-renders on auto-refresh when no visible
data has actually changed.

Add Equatable conformance to BuildRowView, PasteRowView, TicketRowView,
and SelectableTicketRow, and apply .equatable() at each ForEach call
site. When a list does re-render, SwiftUI now skips body evaluation for
rows whose model value is identical to the previous pass.

Implements: https://todo.sr.ht/~ccleberg/hutch/57

1 files changed, 15 insertions, 5 deletions

diff --git a/Hutch/Views/Tickets/TicketListViewModel.swift b/Hutch/Views/Tickets/TicketListViewModel.swift
index e7cc565..e23cc52 100644
--- a/Hutch/Views/Tickets/TicketListViewModel.swift
+++ b/Hutch/Views/Tickets/TicketListViewModel.swift
@@ -83,7 +83,9 @@ final class TicketListViewModel {
     let trackerId: Int
     let trackerRid: String
 
-    private(set) var tickets: [TicketSummary] = []
+    private(set) var tickets: [TicketSummary] = [] {
+        didSet { updateFilteredTickets() }
+    }
     private(set) var isLoading = false
     private(set) var isLoadingMore = false
     private(set) var isCreatingTicket = false
@@ -97,15 +99,21 @@ final class TicketListViewModel {
     var filter: TicketFilter = .open {
         didSet {
             persistFilterState()
+            updateFilteredTickets()
         }
     }
     var selectedLabelIDs: Set<Int> = [] {
         didSet {
             persistFilterState()
+            updateFilteredTickets()
         }
     }
-    var searchText = ""
+    var searchText = "" {
+        didSet { updateFilteredTickets() }
+    }
     private(set) var activeSavedFilterID: SavedTicketFilter.ID?
+    // Cached filtered result. See updateFilteredTickets().
+    private(set) var filteredTickets: [TicketSummary] = []
 
     private var cursor: String?
     private var hasMore = true
@@ -268,9 +276,11 @@ final class TicketListViewModel {
         !currentFilterState.isDefault
     }
 
-    /// Tickets filtered by the selected status and label filters.
-    var filteredTickets: [TicketSummary] {
-        Self.filterTickets(tickets, state: currentFilterState, query: searchText)
+    private func updateFilteredTickets() {
+        let updated = Self.filterTickets(tickets, state: currentFilterState, query: searchText)
+        if updated != filteredTickets {
+            filteredTickets = updated
+        }
     }
 
     // MARK: - Public API