feat: inventory system, adventure scene engine, and PC generator fixes

- Inventory: items linked to PCs with name, qty, ENC, category; effective
  FP = STR+CON minus total ENC carried; CRUD API + inline UI on Characters tab
- Adventure scene engine: new tab with procedural CYOA choices (Fight, Sneak,
  Talk, Investigate, Flee) resolved via skill checks; scenes generated from
  any rollable table with automatic L2 cascade; scene state persisted in DB
- Fix total HP formula: was CON+SIZ, now correctly ceil((CON+SIZ)/2) per RQ3
- Fix hit location HPs: were computed from wrong total HP, now correct
- Add fatigue points (STR+CON) to derived stats
- Add all seven skill category modifiers computed from characteristics
  (primary/secondary/negative influences per rulebook), shown in generator UI
- Add base skill computation (computeBaseSkills) for use in scene engine
- Add RQ3 Players Book to docs/ as reference

db.js

@@ -96,6 +96,34 @@ CREATE TABLE IF NOT EXISTS enemies (
   updated_at TEXT NOT NULL DEFAULT (datetime('now'))
 );
 
+CREATE TABLE IF NOT EXISTS inventory_items (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  character_id INTEGER NOT NULL REFERENCES player_characters(id) ON DELETE CASCADE,
+  name TEXT NOT NULL,
+  quantity INTEGER NOT NULL DEFAULT 1,
+  enc REAL NOT NULL DEFAULT 0,
+  category TEXT NOT NULL DEFAULT 'equipment',
+  notes TEXT,
+  created_at TEXT NOT NULL DEFAULT (datetime('now'))
+);
+CREATE INDEX IF NOT EXISTS idx_inventory_character ON inventory_items(character_id);
+
+CREATE TABLE IF NOT EXISTS adventure_state (
+  id INTEGER PRIMARY KEY CHECK (id = 1),
+  character_id INTEGER REFERENCES player_characters(id),
+  scene_json TEXT NOT NULL,
+  updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS player_characters (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  name TEXT NOT NULL,
+  generation_method TEXT NOT NULL DEFAULT 'random',
+  stat_block_id INTEGER NOT NULL REFERENCES stat_blocks(id) ON DELETE CASCADE,
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
 CREATE TABLE IF NOT EXISTS log_entries (
   id INTEGER PRIMARY KEY AUTOINCREMENT,
   type TEXT NOT NULL,
@@ -352,6 +380,88 @@ function deleteEnemy(id) {
   return true;
 }
 
+// ---------- inventory ----------
+
+function listInventory(characterId) {
+  return db.prepare('SELECT * FROM inventory_items WHERE character_id = ? ORDER BY category, name').all(characterId);
+}
+
+function addInventoryItem({ character_id, name, quantity = 1, enc = 0, category = 'equipment', notes = null }) {
+  const info = db.prepare(`
+    INSERT INTO inventory_items (character_id, name, quantity, enc, category, notes)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `).run(character_id, name, quantity, enc, category, notes);
+  return db.prepare('SELECT * FROM inventory_items WHERE id = ?').get(info.lastInsertRowid);
+}
+
+function updateInventoryItem(id, { quantity, enc, notes }) {
+  const item = db.prepare('SELECT * FROM inventory_items WHERE id = ?').get(id);
+  if (!item) return null;
+  db.prepare(`UPDATE inventory_items SET quantity=?, enc=?, notes=? WHERE id=?`).run(
+    quantity ?? item.quantity, enc ?? item.enc, notes !== undefined ? notes : item.notes, id
+  );
+  return db.prepare('SELECT * FROM inventory_items WHERE id = ?').get(id);
+}
+
+function deleteInventoryItem(id) {
+  return db.prepare('DELETE FROM inventory_items WHERE id = ?').run(id).changes > 0;
+}
+
+function inventoryTotalEnc(characterId) {
+  const row = db.prepare('SELECT SUM(quantity * enc) AS total FROM inventory_items WHERE character_id = ?').get(characterId);
+  return row ? (row.total || 0) : 0;
+}
+
+// ---------- adventure state ----------
+
+function getAdventureState() {
+  const row = db.prepare('SELECT * FROM adventure_state WHERE id = 1').get();
+  if (!row) return null;
+  return { characterId: row.character_id, scene: JSON.parse(row.scene_json) };
+}
+
+function setAdventureState(characterId, scene) {
+  db.prepare(`
+    INSERT INTO adventure_state (id, character_id, scene_json, updated_at) VALUES (1, ?, ?, datetime('now'))
+    ON CONFLICT(id) DO UPDATE SET character_id=?, scene_json=?, updated_at=datetime('now')
+  `).run(characterId, JSON.stringify(scene), characterId, JSON.stringify(scene));
+  return getAdventureState();
+}
+
+function clearAdventureState() {
+  db.prepare('DELETE FROM adventure_state WHERE id = 1').run();
+}
+
+// ---------- player characters ----------
+
+function listPlayerCharacters() {
+  const rows = db.prepare('SELECT * FROM player_characters ORDER BY id DESC').all();
+  return rows.map((r) => ({ ...r, stat_block: getStatBlock(r.stat_block_id) }));
+}
+
+function getPlayerCharacter(id) {
+  const row = db.prepare('SELECT * FROM player_characters WHERE id = ?').get(id);
+  if (!row) return null;
+  return { ...row, stat_block: getStatBlock(row.stat_block_id) };
+}
+
+function createPlayerCharacter({ name, generation_method, stat_block }) {
+  const statBlockId = createStatBlock(stat_block || {}).id;
+  const info = db.prepare(`
+    INSERT INTO player_characters (name, generation_method, stat_block_id)
+    VALUES (?, ?, ?)
+  `).run(name, generation_method ?? 'random', statBlockId);
+  return getPlayerCharacter(info.lastInsertRowid);
+}
+
+function deletePlayerCharacter(id) {
+  const existing = getPlayerCharacter(id);
+  if (!existing) return false;
+  db.prepare('DELETE FROM player_characters WHERE id = ?').run(id);
+  deleteStatBlock(existing.stat_block_id);
+  return true;
+}
+
 // ---------- log ----------
 
 function appendLogEntry({ type, summary, details }) {
@@ -581,6 +691,9 @@ module.exports = {
   },
   npcs: { list: listNpcs, get: getNpc, create: createNpc, update: updateNpc, delete: deleteNpc, linkStatBlock: linkNpcStatBlock },
   enemies: { list: listEnemies, get: getEnemy, create: createEnemy, update: updateEnemy, delete: deleteEnemy },
+  playerCharacters: { list: listPlayerCharacters, get: getPlayerCharacter, create: createPlayerCharacter, delete: deletePlayerCharacter },
+  inventory: { list: listInventory, add: addInventoryItem, update: updateInventoryItem, delete: deleteInventoryItem, totalEnc: inventoryTotalEnc },
+  adventure: { get: getAdventureState, set: setAdventureState, clear: clearAdventureState },
   log: { append: appendLogEntry, get: getLogEntry, search: searchLog },
   combat: { get: getCombatState, set: setCombatState, clear: clearCombatState },
   tables: {