sx-pub Phase 2: publish to IPFS, browse collections, resolve by path + CID

New endpoints:
- POST /pub/publish — pin SX content to IPFS, store path→CID in DB
- GET /pub/browse/<collection> — list published documents
- GET /pub/doc/<collection>/<slug> — resolve path to CID, fetch from IPFS
- GET /pub/cid/<cid> — direct CID fetch (immutable, cache forever)

New helpers: pub-publish, pub-collection-items, pub-resolve-document, pub-fetch-cid

Tested: published stdlib.sx (6.9KB) → QmQQyR3Ltqi5sFiwZh5dutPbAM4QsEBnw419RyNnTj4fFM

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sxc/pages/helpers.py

@@ -41,6 +41,10 @@ def _register_sx_helpers() -> None:
         "pub-actor-data": _pub_actor_data,
         "pub-collections-data": _pub_collections_data,
         "pub-status-data": _pub_status_data,
+        "pub-publish": _pub_publish,
+        "pub-collection-items": _pub_collection_items,
+        "pub-resolve-document": _pub_resolve_document,
+        "pub-fetch-cid": _pub_fetch_cid,
     })
 
 
@@ -1740,3 +1744,23 @@ async def _pub_collections_data():
 async def _pub_status_data():
     from .pub_helpers import check_status
     return await check_status()
+
+
+async def _pub_publish(collection, slug, content, title="", summary=""):
+    from .pub_helpers import publish_document
+    return await publish_document(collection, slug, content, title, summary)
+
+
+async def _pub_collection_items(collection_slug):
+    from .pub_helpers import collection_items
+    return await collection_items(collection_slug)
+
+
+async def _pub_resolve_document(collection_slug, slug):
+    from .pub_helpers import resolve_document
+    return await resolve_document(collection_slug, slug)
+
+
+async def _pub_fetch_cid(cid):
+    from .pub_helpers import fetch_cid
+    return await fetch_cid(cid)