Add mesh-knowledge, the knowledge base's first slice (hq issue 425, ADR 0290)

An agent learns what a decision says only by reading whole records. This module
holds every decision record and research effort whole in a database in the store,
with clauses that carry their own status and source, typed links read from both
ends, and every version. It answers ask, get and holds within a stated bound, and
takes a record through reserve, propose (refused on any of the 29 per-record
rules), review by someone other than the author, and acceptance, on the
operator's proven warrant when the record needs it. The 4 whole-set rules make
the module unhealthy when they fail. The import reads hq at a commit through the
records module, never overwrites, and changes nothing when run again. Prose
decisions get drafted clauses that a second judgement must confirm before they
are served.

modules/mesh-knowledge/cmd/mesh-knowledge/schema.sql

@@ -0,0 +1,73 @@
+-- The consolidated schema of the knowledge base: what a fresh database is given at once, and what every
+-- migration in migrations/ applied in order comes to (the test TestTheConsolidatedSchemaIsTheMigrationsApplied
+-- holds the two equal). Consolidated through migration 0001.
+
+create table record (
+    kind            text        not null check (kind in ('decision', 'research')),
+    number          integer     not null check (number > 0),
+    status          text        not null,
+    topic           text        not null default '',
+    current_version integer     not null,
+    pending_version integer,
+    revision        bigint      not null default 1,
+    search          tsvector    not null default ''::tsvector,
+    primary key (kind, number)
+);
+
+create index record_search on record using gin (search);
+create index record_topic on record (topic);
+
+create table version (
+    kind    text        not null,
+    number  integer     not null,
+    n       integer     not null check (n > 0),
+    by      text        not null,
+    at      timestamptz not null,
+    why     text        not null,
+    insight boolean     not null default false,
+    body    jsonb       not null,
+    primary key (kind, number, n),
+    foreign key (kind, number) references record (kind, number)
+);
+
+create table clause (
+    kind   text     not null,
+    number integer  not null,
+    n      integer  not null check (n > 0),
+    text   text     not null,
+    status text     not null,
+    source text     not null,
+    search tsvector not null,
+    primary key (kind, number, n),
+    foreign key (kind, number) references record (kind, number)
+);
+
+create index clause_search on clause using gin (search);
+
+create table link (
+    from_kind   text    not null,
+    from_number integer not null,
+    from_clause integer not null default 0,
+    kind        text    not null,
+    to_kind     text    not null,
+    to_number   integer not null default 0,
+    to_clause   integer not null default 0,
+    to_path     text    not null default '',
+    body        jsonb   not null,
+    foreign key (from_kind, from_number) references record (kind, number)
+);
+
+create index link_from on link (from_kind, from_number);
+create index link_to on link (to_kind, to_number);
+
+create table finding (
+    rule    text        not null,
+    records text[]      not null,
+    says    text        not null,
+    at      timestamptz not null
+);
+
+create table told (
+    topic text        primary key,
+    at    timestamptz not null default now()
+);