feat(views): wire derived views onto InformationSpace + integration (WP-0010 T5)

Expose backlinks(name), recent_changes(), all_pages(), site_map() on
InformationSpace. Integration test exercises all four over two shards (BackLinks
aggregate across shards, AllPages/SiteMap span the union, RecentChanges merges an
alias decision with shard edits). SCOPE updated; WP-0010 done. 152 tests green.

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

src/shard_wiki/space.py

@@ -23,6 +23,16 @@ from shard_wiki.coordination import (
 from shard_wiki.model import Page
 from shard_wiki.policy import DEFAULT_POLICY, Policy
 from shard_wiki.union import Resolution, UnionGraph
+from shard_wiki.views import (
+    AllPagesEntry,
+    BackLink,
+    ChangeEntry,
+    SiteMapNode,
+    all_pages,
+    build_backlinks,
+    recent_changes,
+    site_map,
+)
 
 __all__ = ["InformationSpace"]
 
@@ -92,3 +102,21 @@ class InformationSpace:
         draft as local truth (I-5: overlay before mutation, always)."""
         overlay = self.overlay(name, body, actor=actor)
         return self.apply_overlay(overlay.overlay_id)
+
+    # --- derived views (SHARD-WP-0010): recomputable, provenance-carrying, presentation-free ---
+
+    def backlinks(self, name: str, *, camelcase: bool = False) -> tuple[BackLink, ...]:
+        """Pages across the union that link to ``name`` (UC-18)."""
+        return build_backlinks(self.union, camelcase=camelcase).to(name)
+
+    def recent_changes(self, *, limit: int | None = None) -> tuple[ChangeEntry, ...]:
+        """The merged newest-first change feed: coordination journal + shard signals (UC-17)."""
+        return recent_changes(self.union, self.log, self.space_id, limit=limit)
+
+    def all_pages(self) -> tuple[AllPagesEntry, ...]:
+        """The union's distinct pages, chorus/equivalence-collapsed with divergence noted."""
+        return all_pages(self.union)
+
+    def site_map(self) -> SiteMapNode:
+        """The union namespace tree built from page placements."""
+        return site_map(self.union)