feat(space): InformationSpace orchestrator + integration; foundation slice complete (WP-0007 T7)

InformationSpace ties the slice together: conformance-gated attach → resolve →
read, with alias() recording coordination decisions in the log. Exposed from the
package root. End-to-end integration test (two folder shards → union read with
layered provenance + chorus + alias redirect + red-link + nonconformant-rejected).
pyflakes clean, 39 tests green. Flips WP-0007 done.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/shard_wiki/space.py

@@ -0,0 +1,42 @@
+"""InformationSpace — the thin orchestrator entry tying the slice together (blueprint §3 L6).
+
+A root entity / information space: shards attach to it (conformance-gated, TSD §A.2), a
+coordination decision log records its canonical decisions, and a derived union resolves names to
+pages. This is the L6 consumer surface for the foundation slice (attach → resolve → read);
+a network API is a later workplan.
+"""
+
+from __future__ import annotations
+
+from shard_wiki.adapters import ShardAdapter, assert_conformant
+from shard_wiki.coordination import DecisionLog, EventType
+from shard_wiki.model import Page
+from shard_wiki.policy import DEFAULT_POLICY, Policy
+from shard_wiki.union import Resolution, UnionGraph
+
+__all__ = ["InformationSpace"]
+
+
+class InformationSpace:
+    def __init__(self, space_id: str, policy: Policy = DEFAULT_POLICY) -> None:
+        self.space_id = space_id
+        self.log = DecisionLog()
+        self.union = UnionGraph(space_id, log=self.log, policy=policy)
+
+    def attach(self, adapter: ShardAdapter) -> None:
+        """Attach a shard — only if it passes conformance (verified profile, I-3/§6.6)."""
+        assert_conformant(adapter)
+        self.union.attach(adapter)
+
+    def alias(self, name: str, target: str, actor: str | None = None) -> None:
+        """Record a coordination-canonical alias (``name`` → ``"shard:key"``) in the log."""
+        self.log.append(
+            self.space_id, EventType.ALIAS_SET, {"alias": name, "target": target}, actor=actor
+        )
+
+    def resolve(self, name: str) -> Resolution:
+        return self.union.resolve(name)
+
+    def read(self, name: str) -> Page:
+        """Resolve and return the page (or the canonical pick of a chorus). KeyError if red-link."""
+        return self.union.resolve(name).single()