fix(acl): make shared records findable, not just openable (#2079)

Option A of the #2079 fork, per the operator's call: widen the scope in
query_knowledge for every caller rather than special-casing the snippet path.

Until now the list/search queries filtered on Note.user_id alone, while
get_note_permission resolved shares properly. The result: a record shared with
you could be OPENED by id but never FOUND — invisible in Knowledge browse, in
snippet and process lists, and in the facet counts beside them.

- services/access.py gains readable_notes_clause(user_id): the same resolution
  get_note_permission does per row (ownership, direct share, group share,
  inherited project share), expressed as set membership so a list query can use
  it in one statement instead of O(n) permission round-trips.
- services/knowledge.py routes every query through it — query_knowledge, the
  keyword half of the hybrid search, query_knowledge_ids, get_knowledge_by_ids,
  get_knowledge_tags and get_knowledge_counts. The facets follow the list, or a
  tag visible in the list would filter it down to nothing.
- list items now carry user_id, since these lists can be mixed-ownership and
  the client has no other way to mark what isn't yours.

Reaches four surfaces: the Snippets list (the original report), Knowledge
browse, list_processes, and the plugin's process manifest — so a Process shared
with you now also syncs as a local skill stub, which is the point of sharing one.

NOT widened: semantic_search_notes, which scopes by NoteEmbedding.user_id and
also backs auto-inject and the search MCP tool. Widening it would put another
user's content into your agent context automatically — a product decision, not
a bug fix. Consequence until that call is made, marked at the call site: a
shared record is findable by wording but not by meaning.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RLwAaV4DQEmVyn496HnEvt

src/scribe/services/access.py

@@ -9,7 +9,7 @@ Permission rank: owner > admin > editor > viewer
 
 import logging
 
-from sqlalchemy import select
+from sqlalchemy import or_, select
 
 from scribe.models import async_session
 from scribe.models.group import GroupMembership
@@ -161,3 +161,43 @@ async def can_read_note(user_id: int, note_id: int) -> bool:
 async def can_write_note(user_id: int, note_id: int) -> bool:
     perm = await get_note_permission(user_id, note_id)
     return perm in ("editor", "admin", "owner")
+
+
+# ---------------------------------------------------------------------------
+# Set-based visibility (for LIST queries)
+# ---------------------------------------------------------------------------
+
+async def readable_notes_clause(user_id: int):
+    """A SQLAlchemy WHERE predicate matching every note this user may READ.
+
+    `get_note_permission` answers "may I read THIS note?" one row at a time,
+    which a list query can't use — checking per row is O(n) round-trips. This is
+    the same resolution expressed as set membership so it can go straight into a
+    `select(Note).where(...)`:
+
+        1. ownership
+        2. a direct note share
+        3. a group note share
+        4. inheritance from a shared project
+
+    Keep the two in step: a rule added here belongs in `get_note_permission`
+    too, or a note becomes findable but not openable (or the reverse — which is
+    the bug this was written to fix).
+    """
+    async with async_session() as session:
+        group_ids = await _user_group_ids(session, user_id)
+
+    note_share_conds = [NoteShare.shared_with_user_id == user_id]
+    project_share_conds = [ProjectShare.shared_with_user_id == user_id]
+    if group_ids:
+        note_share_conds.append(NoteShare.shared_with_group_id.in_(group_ids))
+        project_share_conds.append(ProjectShare.shared_with_group_id.in_(group_ids))
+
+    shared_note_ids = select(NoteShare.note_id).where(or_(*note_share_conds))
+    shared_project_ids = select(ProjectShare.project_id).where(or_(*project_share_conds))
+
+    return or_(
+        Note.user_id == user_id,
+        Note.id.in_(shared_note_ids),
+        Note.project_id.in_(shared_project_ids),
+    )