Add self-hosted kids calendar app

Express + SQLite (node:sqlite, no native build step) family calendar:
parent accounts with household invites, per-child calendars with
save/duplicate/print, a token-gated read-only kiosk view for tablets,
and polling to keep parent and kiosk views in sync. Defaults to port 3007.

src/db/schema.sql

@@ -0,0 +1,76 @@
+CREATE TABLE IF NOT EXISTS households (
+  id         INTEGER PRIMARY KEY AUTOINCREMENT,
+  name       TEXT NOT NULL,
+  created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+
+CREATE TABLE IF NOT EXISTS parents (
+  id            INTEGER PRIMARY KEY AUTOINCREMENT,
+  household_id  INTEGER NOT NULL REFERENCES households(id) ON DELETE CASCADE,
+  email         TEXT NOT NULL UNIQUE COLLATE NOCASE,
+  password_hash TEXT NOT NULL,
+  name          TEXT NOT NULL,
+  created_at    TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+CREATE INDEX IF NOT EXISTS idx_parents_household ON parents(household_id);
+
+CREATE TABLE IF NOT EXISTS household_invites (
+  id                    INTEGER PRIMARY KEY AUTOINCREMENT,
+  household_id          INTEGER NOT NULL REFERENCES households(id) ON DELETE CASCADE,
+  token                 TEXT NOT NULL UNIQUE,
+  created_by_parent_id  INTEGER NOT NULL REFERENCES parents(id) ON DELETE CASCADE,
+  expires_at            TEXT NOT NULL,
+  used_at               TEXT,
+  used_by_parent_id     INTEGER REFERENCES parents(id),
+  created_at            TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+CREATE INDEX IF NOT EXISTS idx_invites_household ON household_invites(household_id);
+
+CREATE TABLE IF NOT EXISTS children (
+  id                  INTEGER PRIMARY KEY AUTOINCREMENT,
+  household_id        INTEGER NOT NULL REFERENCES households(id) ON DELETE CASCADE,
+  name                TEXT NOT NULL,
+  kiosk_token         TEXT NOT NULL UNIQUE,
+  active_calendar_id  INTEGER REFERENCES calendars(id) ON DELETE SET NULL,
+  created_at          TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+CREATE INDEX IF NOT EXISTS idx_children_household ON children(household_id);
+
+CREATE TABLE IF NOT EXISTS calendars (
+  id               INTEGER PRIMARY KEY AUTOINCREMENT,
+  child_id         INTEGER NOT NULL REFERENCES children(id) ON DELETE CASCADE,
+  title            TEXT NOT NULL,
+  week_start_date  TEXT,
+  show_weekend     INTEGER NOT NULL DEFAULT 0,
+  updated_at       TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
+  created_at       TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+CREATE INDEX IF NOT EXISTS idx_calendars_child ON calendars(child_id);
+
+CREATE TABLE IF NOT EXISTS calendar_blocks (
+  calendar_id INTEGER NOT NULL REFERENCES calendars(id) ON DELETE CASCADE,
+  block_key   TEXT NOT NULL CHECK (block_key IN ('morning','school','after','evening')),
+  label       TEXT NOT NULL,
+  PRIMARY KEY (calendar_id, block_key)
+);
+
+CREATE TABLE IF NOT EXISTS calendar_tasks (
+  id          INTEGER PRIMARY KEY AUTOINCREMENT,
+  calendar_id INTEGER NOT NULL REFERENCES calendars(id) ON DELETE CASCADE,
+  day_of_week TEXT NOT NULL CHECK (day_of_week IN
+              ('Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday')),
+  block_key   TEXT NOT NULL CHECK (block_key IN ('morning','school','after','evening')),
+  text        TEXT NOT NULL,
+  done        INTEGER NOT NULL DEFAULT 0,
+  sort_order  INTEGER NOT NULL DEFAULT 0,
+  updated_at  TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
+  created_at  TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+);
+CREATE INDEX IF NOT EXISTS idx_tasks_calendar ON calendar_tasks(calendar_id, day_of_week, block_key);
+
+CREATE TABLE IF NOT EXISTS sessions (
+  sid        TEXT PRIMARY KEY,
+  sess       TEXT NOT NULL,
+  expires_at INTEGER NOT NULL
+);
+CREATE INDEX IF NOT EXISTS idx_sessions_expires ON sessions(expires_at);