feat: add the relationship graph with extraction, corrections and explorer

Phase 11. Entities are mind-scoped nodes with canonical matching,
aliases and deterministic kind guessing (hostnames and hyphenated ids
are systems, capitalised names people, file suffixes documents).
Relationships carry a relation from the shared vocabulary, confidence,
source, reinforcement count and the event that produced them; links tie
entities to memories, beliefs, events, goals and predictions.

The perceive and attend handlers upsert the entities a message or
observation mentions and record co-mention edges cited to the event, so
the graph grows only from what was actually seen. Operators can merge
("these are the same": edges and links move, the old name becomes an
alias, the old id still resolves), record that two entities are
different, correct kinds and add typed edges; every correction is an
operator action and a corrections row.

The explorer renders a bounded subgraph on a canvas with a small
force-directed layout in plain JavaScript, with kind filters, focus on
a neighbourhood and a side panel per entity. API, entity page, CLI and
docs/graph.md.

internal/graph/graph_test.go

@@ -0,0 +1,85 @@
+package graph
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/andydixon/noema/internal/minds"
+	"github.com/andydixon/noema/internal/storage"
+	"github.com/andydixon/noema/migrations"
+	"github.com/andydixon/noema/pkg/concepts"
+	"github.com/andydixon/noema/pkg/ids"
+)
+
+func TestGuessKindAndCanonical(t *testing.T) {
+	cases := map[string]Kind{"atlas.local": System, "server-01": System, "web-api-prod": System, "Andy": Person, "report.pdf": Document, "andydixon/noema": Repository, "latency": Concept}
+	for name, want := range cases {
+		if got := GuessKind(name); got != want {
+			t.Errorf("%s: got %s want %s", name, got, want)
+		}
+	}
+	if Canonical("  Atlas,  ") != "atlas" {
+		t.Fatal("canonical wrong")
+	}
+}
+
+func TestUpsertRelateMergeAndIsolation(t *testing.T) {
+	pool := storage.TestPool(t, migrations.FS)
+	ctx := context.Background()
+	ms := minds.NewStore(pool)
+	a, _ := ms.Create(ctx, minds.CreateParams{Slug: "a"})
+	b, _ := ms.Create(ctx, minds.CreateParams{Slug: "b"})
+	s := NewStore(pool)
+	now := time.Now()
+	andy, _ := s.Upsert(ctx, pool, a.ID, "", "Andy", now)
+	andy2, _ := s.Upsert(ctx, pool, a.ID, "", "andy", now)
+	if andy.ID != andy2.ID || andy2.MentionCount != 2 || andy.Kind != Person {
+		t.Fatalf("upsert dedupe wrong: %+v %+v", andy, andy2)
+	}
+	atlas, _ := s.Upsert(ctx, pool, a.ID, "", "atlas", now)
+	atlasHost, _ := s.Upsert(ctx, pool, a.ID, "", "atlas.local", now)
+	if _, err := s.Relate(ctx, pool, a.ID, andy.ID, atlas.ID, concepts.DiscussedWith, 0.3, "co-mention", ids.Nil); err != nil {
+		t.Fatal(err)
+	}
+	r2, _ := s.Relate(ctx, pool, a.ID, andy.ID, atlas.ID, concepts.DiscussedWith, 0.6, "co-mention", ids.Nil)
+	_ = r2
+	nb, _ := s.Neighbourhood(ctx, a.ID, andy.ID, 10)
+	if len(nb) != 1 || nb[0].Count != 2 || nb[0].Confidence != 0.6 {
+		t.Fatalf("relate reinforcement wrong: %+v", nb)
+	}
+	// Cross-mind endpoints are refused.
+	other, _ := s.Upsert(ctx, pool, b.ID, "", "atlas", now)
+	if _, err := s.Relate(ctx, pool, a.ID, andy.ID, other.ID, concepts.RelatedTo, 0.5, "x", ids.Nil); err == nil {
+		t.Fatal("cross-mind edge accepted")
+	}
+	if _, err := s.Get(ctx, b.ID, andy.ID); err == nil {
+		t.Fatal("cross-mind get")
+	}
+	// Merge atlas.local into atlas; old id still resolves; alias matches.
+	s.Relate(ctx, pool, a.ID, atlasHost.ID, andy.ID, concepts.BelongsTo, 0.5, "x", ids.Nil) //nolint:errcheck
+	s.LinkRef(ctx, pool, a.ID, atlasHost.ID, "memory", ids.New())                           //nolint:errcheck
+	if err := s.Merge(ctx, a.ID, atlas.ID, atlasHost.ID); err != nil {
+		t.Fatal(err)
+	}
+	got, err := s.Get(ctx, a.ID, atlasHost.ID)
+	if err != nil || got.ID != atlas.ID || len(got.Aliases) == 0 {
+		t.Fatalf("merge resolution wrong: %v %+v", err, got)
+	}
+	again, _ := s.Upsert(ctx, pool, a.ID, "", "atlas.local", now)
+	if again.ID != atlas.ID {
+		t.Fatal("alias did not match after merge")
+	}
+	links, _ := s.Links(ctx, a.ID, atlas.ID, 10)
+	if len(links) != 1 {
+		t.Fatalf("links not moved: %d", len(links))
+	}
+	sg, _ := s.Subgraph(ctx, a.ID, ids.Nil, "", 50)
+	if len(sg.Nodes) != 2 || len(sg.Edges) < 1 || sg.Total != 2 {
+		t.Fatalf("subgraph wrong: %d nodes %d edges total %d", len(sg.Nodes), len(sg.Edges), sg.Total)
+	}
+	st, _ := s.Stats(ctx, a.ID)
+	if st.Entities != 2 || st.ByKind["person"] != 1 {
+		t.Fatalf("stats: %+v", st)
+	}
+}