feat: initialize k-tv-frontend with Next.js and Tailwind CSS

- Added package.json with dependencies and scripts for development, build, and linting.
- Created postcss.config.mjs for Tailwind CSS integration.
- Added SVG assets for UI components including file, globe, next, vercel, and window icons.
- Configured TypeScript with tsconfig.json for strict type checking and module resolution.

k-tv-backend/migrations_sqlite/20240101000000_init_users.sql

@@ -0,0 +1,11 @@
+-- Create users table
+CREATE TABLE IF NOT EXISTS users (
+    id TEXT PRIMARY KEY NOT NULL,
+    subject TEXT NOT NULL,
+    email TEXT NOT NULL,
+    password_hash TEXT,
+    created_at TEXT NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_users_subject ON users(subject);
+CREATE UNIQUE INDEX IF NOT EXISTS idx_users_email ON users(email);

k-tv-backend/migrations_sqlite/20240102000000_init_channels.sql

@@ -0,0 +1,59 @@
+-- Channels: user-defined broadcast channels with their schedule template
+CREATE TABLE IF NOT EXISTS channels (
+    id              TEXT PRIMARY KEY NOT NULL,
+    owner_id        TEXT NOT NULL,
+    name            TEXT NOT NULL,
+    description     TEXT,
+    timezone        TEXT NOT NULL DEFAULT 'UTC',
+    -- JSON-encoded ScheduleConfig (the shareable/exportable template)
+    schedule_config TEXT NOT NULL DEFAULT '{"blocks":[]}',
+    -- JSON-encoded RecyclePolicy
+    recycle_policy  TEXT NOT NULL DEFAULT '{"cooldown_days":30,"cooldown_generations":null,"min_available_ratio":0.2}',
+    created_at      TEXT NOT NULL,
+    updated_at      TEXT NOT NULL
+);
+
+CREATE INDEX IF NOT EXISTS idx_channels_owner ON channels(owner_id);
+
+-- Generated 48-hour schedules (resolved from a channel's template)
+CREATE TABLE IF NOT EXISTS generated_schedules (
+    id          TEXT    PRIMARY KEY NOT NULL,
+    channel_id  TEXT    NOT NULL,
+    valid_from  TEXT    NOT NULL,
+    valid_until TEXT    NOT NULL,
+    generation  INTEGER NOT NULL,
+    FOREIGN KEY (channel_id) REFERENCES channels(id) ON DELETE CASCADE
+);
+
+-- Composite index supports both "find active at time T" and "find latest"
+CREATE INDEX IF NOT EXISTS idx_schedules_channel_valid
+    ON generated_schedules(channel_id, valid_from DESC);
+
+-- Individual scheduled slots within a generated schedule.
+-- The MediaItem snapshot is stored as JSON so the EPG survives library changes.
+CREATE TABLE IF NOT EXISTS scheduled_slots (
+    id              TEXT PRIMARY KEY NOT NULL,
+    schedule_id     TEXT NOT NULL,
+    start_at        TEXT NOT NULL,
+    end_at          TEXT NOT NULL,
+    -- JSON-encoded MediaItem (metadata snapshot at generation time)
+    item            TEXT NOT NULL,
+    source_block_id TEXT NOT NULL,
+    FOREIGN KEY (schedule_id) REFERENCES generated_schedules(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_slots_schedule_start
+    ON scheduled_slots(schedule_id, start_at);
+
+-- Playback history for the recycle policy engine
+CREATE TABLE IF NOT EXISTS playback_records (
+    id          TEXT    PRIMARY KEY NOT NULL,
+    channel_id  TEXT    NOT NULL,
+    item_id     TEXT    NOT NULL,
+    played_at   TEXT    NOT NULL,
+    generation  INTEGER NOT NULL,
+    FOREIGN KEY (channel_id) REFERENCES channels(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_playback_channel_date
+    ON playback_records(channel_id, played_at DESC);