feat(infospace): add L3 relation graph with VSM-aware triplets (S2.8)

Implements the L3 relation graph layer — a directed graph of (Subject,
Predicate, Object) triplets annotated with VSM channel codes and feedback
roles. Triplets are authored as markdown files under output/relations/,
parsed into RelationMeta dataclasses, and analysed with networkx.

New modules:
- markitect/infospace/relation_models.py — RelationMeta dataclass +
  RELATION_TYPES controlled vocabulary (15 relation classes → VSM codes)
- markitect/infospace/relation_parser.py — parse_relation_file() and
  parse_relations_directory()

New schema: examples/infospace-with-history/schemas/relation-schema-v1.0.md
  — file naming convention, required sections, controlled vocabulary table

15 seed relation files covering the three core WoN feedback loops:
  - Capital Accumulation loop (positive reinforcement, S1/S3)
  - Market Price Balancing loop (negative feedback, S2/S3)
  - Market Extent mutual dependency (S1/S2)
  Plus structural relations: wages regulation, rent residual, price
  decomposition, invisible hand coordination

CLI: markitect infospace relations [--entity SLUG] [--vsm FILTER]
     [--loops] [--stats]
  - Builds directed graph from parsed files
  - Detects feedback loops via nx.simple_cycles()
  - 6 loops found from 15 seed relations (3 intended + 3 emergent)
  - --stats aggregates by VSM system code (strips parentheticals)

Config: InfospaceConfig gains relations_dir (default output/relations)
infospace.yaml: schemas.relation references relation-schema-v1.0.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

markitect/infospace/cli.py

@@ -299,6 +299,126 @@ def eval_summary(config_path: Optional[str], update_metrics: bool):
         click.echo(f"\nUpdated metrics.yaml: per_entity_mean = {mean_overall:.4f}")
 
 
+# ── relations ─────────────────────────────────────────────────────────
+
+
+@infospace_commands.command()
+@click.option("--config", "config_path", default=None, help="Path to infospace.yaml.")
+@click.option("--entity", "entity_slug", default=None,
+              help="Show only relations involving this entity slug.")
+@click.option("--vsm", "vsm_filter", default=None,
+              help="Show only relations whose VSM channel contains this string (e.g. S2, S3).")
+@click.option("--loops", "loops_only", is_flag=True, default=False,
+              help="Show only feedback loops (cycles in the relation graph).")
+@click.option("--stats", "stats_only", is_flag=True, default=False,
+              help="Show aggregate statistics only, no individual relations.")
+def relations(config_path: Optional[str], entity_slug: Optional[str],
+              vsm_filter: Optional[str], loops_only: bool, stats_only: bool):
+    """Show the L3 relation graph — triplets, feedback loops, and VSM channels."""
+    cfg, cfg_path = _load_config_or_exit(config_path)
+    root = cfg_path.parent
+
+    from markitect.infospace.relation_parser import parse_relations_directory
+
+    relations_dir = root / cfg.relations_dir
+    if not relations_dir.is_dir():
+        click.echo("No relations directory found. Create output/relations/ and add relation files.")
+        return
+
+    all_relations = parse_relations_directory(relations_dir)
+    if not all_relations:
+        click.echo("No relation files found in " + str(relations_dir))
+        return
+
+    # Build directed graph for cycle detection
+    try:
+        import networkx as nx
+        G = nx.DiGraph()
+        for r in all_relations:
+            G.add_edge(r.subject_slug, r.object_slug,
+                       predicate=r.predicate,
+                       relation_type=r.relation_type,
+                       vsm_channel=r.vsm_channel,
+                       slug=r.slug)
+    except ImportError:
+        G = None
+
+    # Find feedback loops
+    loops = []
+    if G is not None:
+        try:
+            loops = list(nx.simple_cycles(G))
+        except Exception:
+            loops = []
+
+    # Stats summary
+    import re as _re
+
+    def _vsm_code(channel: str) -> str:
+        """Strip parenthetical description, returning just the system code (e.g. 'S3 → S1')."""
+        return _re.sub(r'\s*\(.*', '', channel).strip() or channel
+
+    n = len(all_relations)
+    vsm_counts: dict = {}
+    type_counts: dict = {}
+    for r in all_relations:
+        vsm_counts[_vsm_code(r.vsm_channel)] = vsm_counts.get(_vsm_code(r.vsm_channel), 0) + 1
+        type_counts[r.relation_type] = type_counts.get(r.relation_type, 0) + 1
+
+    click.echo(f"Relation graph — {n} relations")
+    if G is not None:
+        click.echo(f"  Entities in graph: {G.number_of_nodes()}")
+        click.echo(f"  Feedback loops: {len(loops)}")
+    click.echo()
+
+    if stats_only:
+        click.echo("Relation types:")
+        for rt, count in sorted(type_counts.items(), key=lambda x: -x[1]):
+            click.echo(f"  {rt:<25} {count:>4}")
+        click.echo()
+        click.echo("VSM channels:")
+        for ch, count in sorted(vsm_counts.items(), key=lambda x: -x[1]):
+            click.echo(f"  {ch:<20} {count:>4}")
+        return
+
+    # Feedback loops section
+    if loops or loops_only:
+        if loops:
+            click.echo(f"Feedback loops ({len(loops)}):")
+            for i, cycle in enumerate(loops, 1):
+                click.echo(f"  Loop {i}: {' → '.join(cycle)} → {cycle[0]}")
+            click.echo()
+        elif loops_only:
+            click.echo("No feedback loops detected in current relation set.")
+            return
+
+    if loops_only:
+        return
+
+    # Filter relations
+    filtered = all_relations
+    if entity_slug:
+        filtered = [r for r in filtered
+                    if entity_slug in (r.subject_slug, r.object_slug)]
+        if not filtered:
+            click.echo(f"No relations found involving '{entity_slug}'.")
+            return
+    if vsm_filter:
+        filtered = [r for r in filtered if vsm_filter in r.vsm_channel]
+        if not filtered:
+            click.echo(f"No relations with VSM channel containing '{vsm_filter}'.")
+            return
+
+    # Display relations
+    click.echo(f"{'Subject':<35} {'Predicate':<30} {'Object':<35} {'VSM'}")
+    click.echo("-" * 110)
+    for r in filtered:
+        subj = r.subject[:33] + ".." if len(r.subject) > 35 else r.subject
+        obj = r.object[:33] + ".." if len(r.object) > 35 else r.object
+        pred = r.predicate[:28] + ".." if len(r.predicate) > 30 else r.predicate
+        click.echo(f"{subj:<35} {pred:<30} {obj:<35} {r.vsm_channel}")
+
+
 # ── viability ────────────────────────────────────────────────────────