feat(harness): port vectorstore dual-key + reader RPC (D11, §5.4)

Ports vectorstore/{rest_client,rest_writer,store,reader,embeddings,records},
evidence/model (leaf dep of records), and cli/_guards (require_vector_write_allowed
workstation write-guard). Renamed psdwp3->nsp, verbatim.

VectorRestClient gains an api_key property so reader/writer clients carry their
distinct keys visibly (spec D11: vector_reader / vector_writer on the same endpoint).

scripts/create_vector_reader_rpc.sql is NEW: the reader RPCs (search_similar,
list_tables) lived server-side in Supabase and were never versioned. Authored now
mirroring the writer allowlist pattern (table allowlist, security definer, revoke
from anon/authenticated, grant to vector_reader only). Writer RPC ported verbatim.

L1: test_vector_dual_key (7 tests) pins the dual-key construction + the workstation
write-guard (exit 4 without writer key).

harness/scripts/create_vector_reader_rpc.sql

@@ -0,0 +1,99 @@
+-- RPC reader per pgvector via Supabase/PostgREST (spec D11, §5.4).
+-- Eseguire sul database Supabase centrale come owner dello schema `vectors`.
+-- Prerequisiti:
+--   - schema `vectors` con tabelle schema_records/evidence/memory
+--   - colonne: record_key text unique, kind text, content_hash text, metadata jsonb,
+--     embedding vector(N), indexed_at timestamptz
+--   - ruolo/key PostgREST dedicato `vector_reader` (lettura: search_similar, list_tables)
+--
+-- A differenza del writer RPC (che era gia' nel repo), i reader RPC vivevano lato server
+-- in Supabase e non erano mai stati versionati. Li si riporta qui per completezza del
+-- modello dual-key: la key reader riceve solo EXECUTE su queste due funzioni, niente
+-- SELECT raw sulle tabelle. Il cleanup/rebuild resta solo-server (vedi writer RPC).
+
+create or replace function public._assert_vector_read_table(table_name text)
+returns void
+language plpgsql
+stable
+as $$
+begin
+  if table_name not in ('schema_records', 'evidence', 'memory') then
+    raise sqlstate 'PGRST' using
+      message = json_build_object('message', 'Unsupported vector table')::text,
+      detail = json_build_object('status', 400)::text;
+  end if;
+end;
+$$;
+
+create or replace function public.search_similar(
+  table_name text,
+  query_embedding vector,
+  limit_count integer
+)
+returns table(id bigint, similarity real, metadata jsonb)
+language plpgsql
+security definer
+set search_path = public, vectors, extensions
+as $$
+begin
+  perform public._assert_vector_read_table(table_name);
+  return query execute format(
+    'select t.id,
+            (1 - (t.embedding <=> $1))::real as similarity,
+            t.metadata
+     from vectors.%I t
+     order by t.embedding <=> $1
+     limit $2',
+    table_name
+  ) using query_embedding, limit_count;
+end;
+$$;
+
+create or replace function public.list_tables()
+returns table(table_name text, vector_dimensions integer, record_count bigint)
+language plpgsql
+security definer
+set search_path = public, vectors, extensions
+as $$
+begin
+  return query
+    select c.relname::text as table_name,
+           -- dimensione ricavata dalla colonna embedding (vector(N)) se presente
+           coalesce(
+             (select (regexp_matches(format_type(a.atttypid, a.atttypmod), 'vector\((\d+)\)'))[1])::int,
+             0
+           ) as vector_dimensions,
+           c.reltuples::bigint as record_count
+    from pg_class c
+    join pg_namespace n on n.oid = c.relnamespace
+    left join pg_attribute a on a.attrelid = c.oid and a.attname = 'embedding'
+    where n.nspname = 'vectors'
+      and c.relkind in ('r', 'p')
+      and c.relname in ('schema_records', 'evidence', 'memory')
+    order by c.relname;
+end;
+$$;
+
+revoke all on function public._assert_vector_read_table(text) from public;
+revoke all on function public.search_similar(text, vector, integer) from public;
+revoke all on function public.list_tables() from public;
+
+-- Revoca dai ruoli client generici, poi abilita solo il reader dedicato
+-- (e il writer, che usa existing_vector_hashes per l'upsert incrementale).
+do $$
+begin
+  if exists (select 1 from pg_roles where rolname = 'anon') then
+    revoke all on function public.search_similar(text, vector, integer) from anon;
+    revoke all on function public.list_tables() from anon;
+  end if;
+  if exists (select 1 from pg_roles where rolname = 'authenticated') then
+    revoke all on function public.search_similar(text, vector, integer) from authenticated;
+    revoke all on function public.list_tables() from authenticated;
+  end if;
+  if exists (select 1 from pg_roles where rolname = 'vector_reader') then
+    grant execute on function public.search_similar(text, vector, integer) to vector_reader;
+    grant execute on function public.list_tables() to vector_reader;
+  end if;
+end $$;
+
+notify pgrst, 'reload schema';