T9.8 - D7: archiving stops reading as deletion - for project admins

Archiving already froze a project (the server refuses every write); what did
not exist was the way back in. Now:

- GET /api/projects?archived=only|all filters the answer BY PER-PROJECT ROLE:
  a project admin (or super/app admin) on THAT project sees it; everyone else
  receives an empty list from the same request - archived projects appear
  nowhere for them, counts and pickers included (the default listing already
  excluded them for everyone; asking is what got gated). Admin-on-Job-A does
  not surface archived Job B.
- The launcher gains a visibly separate, labelled "Archived projects"
  section (dashed border, read-only stated in words), rendered only when the
  server returns rows. Opening one makes it active; the launcher's reconcile
  learned that an active project whose stored summary says archived:true was
  opened ON PURPOSE and keeps it, while a project archived out from under
  someone still drops with the existing explanation.
- The creator shows ARCHIVED - READ-ONLY where the project is named (both
  ctx-bar branches, from the SERVER's answer - the page's project comes from
  the URL, so a stale local summary is not trusted) and refuses saves with a
  reason before the round trip. The courtesy; the server's refusal is the
  rule, verified by calling the endpoints directly (wp upsert AND the
  material-list write both refuse with "archived" even for an admin).
- No unarchive button, no second mechanism, and it fits at 390px.

Verification (each probe run alone): NEW tests/archived_check.py 15/15.
Regressions: launcher_check 58/58, sample_check 10/10, export_check 20/20,
frame_check 38/38.

Items: D7

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/app.py

@@ -1294,6 +1294,15 @@ def list_projects(
     elif archived != "all":
         stmt = stmt.where(models.Project.archived_at.is_(None))   # default: hide archived
     rows = db.scalars(stmt.order_by(models.Project.updated_at.desc())).all()
+    # D7 / T9.8: archived projects are readable by PROJECT ADMINS only - anyone
+    # below that sees them nowhere, counts and pickers included. The default
+    # listing already excludes them; asking for them is what gets gated, and it
+    # is gated per project, so admin-on-Job-A does not surface archived Job B.
+    if archived != "exclude":
+        rows = [p for p in rows
+                if p.archived_at is None
+                or effective_role(db, user, p.id) in (
+                    auth.ROLE_ADMIN, auth.ROLE_PROJECT_SUPER, auth.ROLE_PROJECT_ADMIN)]
     return [p.summary() for p in rows]