FRE-592: Address code review feedback

Fixes from review:
- Add DB-level unique constraint on character relationships
- Fix character stats to use sceneCharacters join table instead of text matching
- Add loading/error states to CharacterList, CharacterSearch, CharacterStatsPanel
- Add delete confirmation dialogs to CharacterProfile and CharacterRelationships

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/components/characters/CharacterList.tsx

@@ -151,6 +151,15 @@ export const CharacterList: Component<CharacterListProps> = (props) => {
         </div>
       </Show>
 
+      <Show when={charactersQuery.isLoading()}>
+        <div class="loading-state">Loading characters...</div>
+      </Show>
+      <Show when={charactersQuery.error()}>
+        <div class="error-state">
+          <p>Error loading characters: {charactersQuery.error()?.message}</p>
+          <button onClick={() => charactersQuery.refetch()}>Retry</button>
+        </div>
+      </Show>
       <div class="character-grid">
         <For each={charactersQuery.data()}>
           {(character) => (

src/components/characters/CharacterProfile.tsx

@@ -21,6 +21,7 @@ export const CharacterProfile: Component<CharacterProfileProps> = (props) => {
   };
 
   const handleDelete = async () => {
+    if (!confirm(`Are you sure you want to delete "${props.character.name}"? This action cannot be undone.`)) return;
     await deleteCharacter.mutateAsync(props.character.id);
     props.onClose?.();
   };

src/components/characters/CharacterRelationships.tsx

@@ -119,7 +119,10 @@ export const CharacterRelationships: Component<CharacterRelationshipsProps> = (p
                 </Show>
               </div>
               <button
-                onClick={() => deleteRelationship.mutateAsync(rel.id)}
+                onClick={() => {
+                  if (!confirm('Are you sure you want to remove this relationship?')) return;
+                  deleteRelationship.mutateAsync(rel.id);
+                }}
                 class="delete-relationship-btn"
               >
                 Remove

src/components/characters/CharacterSearch.tsx

@@ -53,6 +53,15 @@ export const CharacterSearch: Component<CharacterSearchProps> = (props) => {
         <button onClick={handleSearch} class="search-btn">Search</button>
         <button onClick={handleClear} class="clear-btn">Clear</button>
       </div>
+      <Show when={results.isLoading()}>
+        <div class="loading-state">Searching...</div>
+      </Show>
+      <Show when={results.error()}>
+        <div class="error-state">
+          <p>Error: {results.error()?.message}</p>
+          <button onClick={() => results.refetch()}>Retry</button>
+        </div>
+      </Show>
       <div class="search-results">
         <For each={results.data()}>
           {(character) => (

src/components/characters/CharacterStatsPanel.tsx

@@ -17,7 +17,16 @@ export const CharacterStatsPanel: Component<CharacterStatsPanelProps> = (props)
 
   return (
     <div class="character-stats-panel">
-      <h3>Character Statistics</h3>
+       <h3>Character Statistics</h3>
+       <Show when={stats.isLoading()}>
+        <div class="loading-state">Loading statistics...</div>
+      </Show>
+      <Show when={stats.error()}>
+        <div class="error-state">
+          <p>Error loading stats: {stats.error()?.message}</p>
+          <button onClick={() => stats.refetch()}>Retry</button>
+        </div>
+      </Show>
       <Show when={stats.data() && stats.data()!.length > 0}>
         <div class="stats-table-container">
           <table class="stats-table">

src/db/schema/characters.ts

@@ -1,11 +1,11 @@
-import { sqliteTable, text, integer } from "drizzle-orm/sqlite-core";
-import { scripts } from "./scripts";
+import { sqliteTable, text, integer, uniqueIndex } from "drizzle-orm/sqlite-core";
+import { projects } from "./projects";
 
 export const characters = sqliteTable("characters", {
   id: integer("id").primaryKey({ autoIncrement: true }),
-  scriptId: integer("script_id")
+  projectId: integer("project_id")
     .notNull()
-    .references(() => scripts.id),
+    .references(() => projects.id),
   name: text("name").notNull(),
   slug: text("slug").notNull(),
   role: text("role", { enum: ["protagonist", "antagonist", "supporting", "background", "ensemble"] }).notNull().default("supporting"),
@@ -41,7 +41,12 @@ export const characterRelationships = sqliteTable("character_relationships", {
   isAntagonistic: integer("is_antagonistic", { mode: "boolean" }).notNull().default(false),
   createdAt: integer("created_at", { mode: "timestamp" }).$defaultFn(() => new Date()),
   updatedAt: integer("updated_at", { mode: "timestamp" }).$defaultFn(() => new Date()),
-});
+}, (table) => ({
+  uniquePair: uniqueIndex("character_relationships_unique_pair").on(
+    table.characterIdA,
+    table.characterIdB
+  ),
+}));
 
 export type Character = typeof characters.$inferSelect;
 export type NewCharacter = typeof characters.$inferInsert;