feat(db): mesh data model — meshes, members, invites, audit log

- pgSchema "mesh" with 4 tables isolating the peer mesh domain
- Enums: visibility, transport, tier, role
- audit_log is metadata-only (E2E encryption enforced at broker/client)
- Cascade on mesh delete, soft-delete via archivedAt/revokedAt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/modules/pdf/hooks/index.ts

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+// PDF Hooks
+
+export { usePdfViewer, useCanGoBack, useCanGoForward } from "../context";
+export { usePdfNavigation } from "./use-pdf-navigation";
+export { useEmbedding } from "./use-embedding";
+export { useCitationUnit } from "./use-citation-unit";
+export type { CitationUnitDetail, BoundingBox } from "./use-citation-unit";

apps/web/src/modules/pdf/hooks/use-citation-unit.ts

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+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+
+import { api } from "~/lib/api/client";
+
+// ============================================================================
+// Types
+// ============================================================================
+
+/**
+ * Bounding box for pixel-perfect highlighting
+ */
+export interface BoundingBox {
+  x: number;
+  y: number;
+  width: number;
+  height: number;
+}
+
+/**
+ * Citation unit with precise location for highlighting (WF-0028)
+ */
+export interface CitationUnitDetail {
+  id: string;
+  content: string;
+  pageNumber: number;
+  paragraphIndex: number;
+  charStart: number;
+  charEnd: number;
+  bbox: BoundingBox | null;
+  sectionTitle: string | null;
+  unitType: string;
+}
+
+// ============================================================================
+// Hook
+// ============================================================================
+
+/**
+ * Fetch citation unit details by ID for bounding box-based highlighting
+ *
+ * Falls back to legacy embedding endpoint if citation unit not found
+ */
+export function useCitationUnit(unitId: string | null) {
+  return useQuery({
+    queryKey: ["pdf", "citation-unit", unitId],
+    queryFn: async (): Promise<CitationUnitDetail | null> => {
+      if (!unitId) return null;
+
+      // Try citation unit endpoint first (WF-0028 dual-resolution)
+      const response = await api.ai.pdf.search["citation-units"].single[":id"].$get({
+        param: { id: unitId },
+      });
+
+      if (response.ok) {
+        const result = await response.json();
+        return (result as { data: CitationUnitDetail }).data;
+      }
+
+      // If not found in citation units, this might be a legacy embedding ID
+      // Return null - the highlight layer will fall back to word overlap
+      if (response.status === 404) {
+        return null;
+      }
+
+      throw new Error("Failed to fetch citation unit");
+    },
+    enabled: Boolean(unitId),
+    staleTime: Infinity, // Citation units don't change
+    gcTime: 1000 * 60 * 30, // Keep in cache for 30 minutes
+  });
+}

apps/web/src/modules/pdf/hooks/use-embedding.ts

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+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+
+import { api } from "~/lib/api/client";
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface EmbeddingDetail {
+  id: string;
+  content: string;
+  pageNumber: number;
+  charStart?: number;
+  charEnd?: number;
+  sectionTitle?: string;
+}
+
+// ============================================================================
+// Hook
+// ============================================================================
+
+/**
+ * Fetch embedding details by ID for citation highlighting
+ */
+export function useEmbedding(embeddingId: string | null) {
+  return useQuery({
+    queryKey: ["pdf", "embedding", embeddingId],
+    queryFn: async (): Promise<EmbeddingDetail | null> => {
+      if (!embeddingId) return null;
+
+      const response = await api.ai.pdf.embeddings[":id"].$get({
+        param: { id: embeddingId },
+      });
+
+      if (!response.ok) {
+        if (response.status === 404) return null;
+        throw new Error("Failed to fetch embedding");
+      }
+
+      return response.json() as Promise<EmbeddingDetail>;
+    },
+    enabled: Boolean(embeddingId),
+    staleTime: Infinity, // Embeddings don't change
+    gcTime: 1000 * 60 * 30, // Keep in cache for 30 minutes
+  });
+}

apps/web/src/modules/pdf/hooks/use-pdf-navigation.ts

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+"use client";
+
+import { useCanGoBack, useCanGoForward, usePdfViewer } from "../context";
+
+/**
+ * Convenience hook for PDF navigation controls.
+ * Combines navigation state and actions in one place.
+ */
+export function usePdfNavigation() {
+  const { goBack, goForward, navigateTo, history, historyIndex } =
+    usePdfViewer();
+  const canGoBack = useCanGoBack();
+  const canGoForward = useCanGoForward();
+
+  return {
+    // Actions
+    goBack,
+    goForward,
+    navigateTo,
+    // State
+    canGoBack,
+    canGoForward,
+    historyLength: history.length,
+    currentIndex: historyIndex,
+  };
+}