Add feed discovery plugin

plugins/feed-discovery/src/db/schema.sql

@@ -0,0 +1,62 @@
+create table if not exists feed_sources (
+  id uuid primary key default gen_random_uuid(),
+  title text not null,
+  description text,
+  homepage_url text,
+  feed_url text not null unique,
+  canonical_feed_url text,
+  kind text not null default 'unknown',
+  provider text not null,
+  language text,
+  image_url text,
+  score numeric not null default 0,
+  confidence numeric not null default 0,
+  freshness_score numeric not null default 0,
+  keyword_score numeric not null default 0,
+  provider_score numeric not null default 0,
+  last_published_at timestamptz,
+  last_checked_at timestamptz,
+  is_valid boolean default true,
+  created_at timestamptz default now(),
+  updated_at timestamptz default now()
+);
+
+create table if not exists feed_discovery_queries (
+  id uuid primary key default gen_random_uuid(),
+  query text not null,
+  normalized_query text not null,
+  type text default 'all',
+  result_count integer not null default 0,
+  created_at timestamptz default now()
+);
+
+create table if not exists feed_discovery_results (
+  query_id uuid references feed_discovery_queries(id) on delete cascade,
+  source_id uuid references feed_sources(id) on delete cascade,
+  rank integer not null,
+  score numeric not null,
+  created_at timestamptz default now(),
+  primary key (query_id, source_id)
+);
+
+create table if not exists feed_items (
+  id uuid primary key default gen_random_uuid(),
+  source_id uuid references feed_sources(id) on delete cascade,
+  title text not null,
+  url text not null unique,
+  description text,
+  published_at timestamptz,
+  guid text,
+  created_at timestamptz default now()
+);
+
+create table if not exists feed_provider_logs (
+  id uuid primary key default gen_random_uuid(),
+  provider text not null,
+  query text not null,
+  status text not null,
+  result_count integer default 0,
+  error_message text,
+  duration_ms integer,
+  created_at timestamptz default now()
+);