feat(02-02): add thread hooks, UI store, tab navigation, and thread list

- Create useThreads/useCandidates TanStack Query hooks
- Extend uiStore with candidate panel and resolve dialog state
- Add ThreadTabs component for gear/planning tab switching
- Add ThreadCard component with candidate count and price range chips
- Refactor index.tsx to tabbed HomePage with PlanningView
- Create placeholder thread detail route for navigation target

src/client/stores/uiStore.ts

@@ -1,6 +1,7 @@
 import { create } from "zustand";
 
 interface UIState {
+  // Item panel state
   panelMode: "closed" | "add" | "edit";
   editingItemId: number | null;
   confirmDeleteItemId: number | null;
@@ -10,9 +11,28 @@ interface UIState {
   closePanel: () => void;
   openConfirmDelete: (itemId: number) => void;
   closeConfirmDelete: () => void;
+
+  // Candidate panel state
+  candidatePanelMode: "closed" | "add" | "edit";
+  editingCandidateId: number | null;
+  confirmDeleteCandidateId: number | null;
+
+  openCandidateAddPanel: () => void;
+  openCandidateEditPanel: (id: number) => void;
+  closeCandidatePanel: () => void;
+  openConfirmDeleteCandidate: (id: number) => void;
+  closeConfirmDeleteCandidate: () => void;
+
+  // Resolution dialog state
+  resolveThreadId: number | null;
+  resolveCandidateId: number | null;
+
+  openResolveDialog: (threadId: number, candidateId: number) => void;
+  closeResolveDialog: () => void;
 }
 
 export const useUIStore = create<UIState>((set) => ({
+  // Item panel
   panelMode: "closed",
   editingItemId: null,
   confirmDeleteItemId: null,
@@ -22,4 +42,29 @@ export const useUIStore = create<UIState>((set) => ({
   closePanel: () => set({ panelMode: "closed", editingItemId: null }),
   openConfirmDelete: (itemId) => set({ confirmDeleteItemId: itemId }),
   closeConfirmDelete: () => set({ confirmDeleteItemId: null }),
+
+  // Candidate panel
+  candidatePanelMode: "closed",
+  editingCandidateId: null,
+  confirmDeleteCandidateId: null,
+
+  openCandidateAddPanel: () =>
+    set({ candidatePanelMode: "add", editingCandidateId: null }),
+  openCandidateEditPanel: (id) =>
+    set({ candidatePanelMode: "edit", editingCandidateId: id }),
+  closeCandidatePanel: () =>
+    set({ candidatePanelMode: "closed", editingCandidateId: null }),
+  openConfirmDeleteCandidate: (id) =>
+    set({ confirmDeleteCandidateId: id }),
+  closeConfirmDeleteCandidate: () =>
+    set({ confirmDeleteCandidateId: null }),
+
+  // Resolution dialog
+  resolveThreadId: null,
+  resolveCandidateId: null,
+
+  openResolveDialog: (threadId, candidateId) =>
+    set({ resolveThreadId: threadId, resolveCandidateId: candidateId }),
+  closeResolveDialog: () =>
+    set({ resolveThreadId: null, resolveCandidateId: null }),
 }));