add scopes subdirectory for (cl-, go-, py-) -scopes storage (tracking) formats

pgsql/scopes/compat_msgstore.sql

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+-- scopes: compat_msgstore
+-- rename columns from go-storage/emsgstore:messages to scopes:messages
+
+alter table messages rename id  to trackid;
+alter table messages rename tstamp  to timestamp;
+alter table messages rename payload  to data;

pgsql/scopes/drop.sql

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+-- drop tables
+
+drop table messages;
+

pgsql/scopes/tables.sql

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+-- scopes: create tables (and other table-related stuff)
+
+CREATE TABLE messages (
+    trackid bigserial NOT NULL primary key,
+    domain text,
+    action text,
+    class text,
+    item text,
+    timestamp timestamptz default current_timestamp,
+    data jsonb
+);
+
+CREATE INDEX idx_msg ON messages USING btree (domain, action, class, item);
+CREATE INDEX idx_msg_item ON messages USING btree (domain, class, item);
+

pgsql/scopes/views.sql

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+-- scopes: create views
+
+create or replace view messages_current as
+  select trackid, domain, action, class, item, timestamp, data
+    from messages m1
+    where trackid = (select max(trackid) from messages m2
+	  where m2.domain = m1.domain and m2.action = m1.action
+	    and m2.class = m1.class and m2.item = m1.item);
+