docs: generate each subsystem's cordis surface into its own page; delete the flat catalogs

Rebuild of the region machinery (PR3) on the post-#904 Typert projection:
renderPageRegion/renderInheritedPage live in dsh-typert-generator beside the
projection; scripts/gen-cordis-catalog.ts owns the curated SERVICE_PAGE /
EVENT_SCOPE_PAGE / SERVICE_WALK_EXEMPTIONS / LINK_MAP partition (fail-loud in
both directions, with the independent Context-merge scan backstopping the
projection's blind spot), spliceRegion, and the guarded pair auto-record.
docs/cordis-catalog/ is deleted: the flat events/services catalogs dissolve
into per-page regions and docs/cordis-catalog/core moves to docs/cordis-api/
with the inherited tier as its own generated page. The partition absorbs the
post-regrouping surface: ctx.typert → invariants.md, ctx.directoryPicker →
workspace.md, skills/* events → skills.md, and the four launcher-provided tui
accessor values join the named exemptions.

scripts/type-equiv.manifest.json

@@ -1679,6 +1679,21 @@
       "doc": "docs/subsystems/permission.md",
       "symbol": "PresetSpec",
       "source": "packages/interaction/permission/src/index.ts"
+    },
+    {
+      "doc": "docs/subsystems/session-projection.md",
+      "symbol": "ProjectionDefinition",
+      "source": "packages/session/session-projection/src/index.ts"
+    },
+    {
+      "doc": "docs/subsystems/session-projection.md",
+      "symbol": "ProjectionSnapshot",
+      "source": "packages/session/session-projection/src/index.ts"
+    },
+    {
+      "doc": "docs/subsystems/session-projection.md",
+      "symbol": "ProjectionChangeListener",
+      "source": "packages/session/session-projection/src/index.ts"
     }
   ]
 }