feat: v2.7.8 — Artifacts hub, clone related repos as extra folders, quieter resume prompt

- Artifacts (/artifacts): claude.ai pages sessions publish (captured from the
  Artifact tool's hook), pinned workspace files, skills and plugins, each
  kept as a snapshot; shared ones appear in a Hub and a skill or plugin
  installs into the viewer's own account (server/lib/artifacts.js,
  /api/artifacts, docs/plans/artifacts/).
- Workspace extra folders: clone one or more related repos beside the
  workspace and add them in one step (POST /api/lanes/:id/sources/clone).
- A pane that ended by itself while tmux kept running is no longer offered
  for resume (tmux.serverStartedAt in reconcileOrphans).
- Changes panel: a folder that is not a git repo opens on Files, and its
  files open from there.
- Plus the parallel sessions' work in this tree: File Explorer button in the
  panel header, user delete, RSA SSH keys, chat/terminal and pet fixes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/db.js

@@ -914,6 +914,37 @@ db.exec(`
   CREATE INDEX IF NOT EXISTS idx_lane_sources_lane ON lane_sources(lane_id);
 `);
 
+// The Artifacts hub (server/lib/artifacts.js, docs/plans/artifacts/): what
+// agents produced — a claude.ai page, a file, a skill, a plugin — kept by its
+// OWNER and, in server mode, shared to every user when `shared` is set. A
+// file or skill is a snapshot under <data dir>/artifacts/<snapshot>/, never
+// the owner's live copy. Additive.
+db.exec(`
+  CREATE TABLE IF NOT EXISTS artifacts (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    kind TEXT NOT NULL CHECK (kind IN ('page', 'file', 'skill', 'plugin')),
+    title TEXT NOT NULL,
+    description TEXT NOT NULL DEFAULT '',
+    owner_id INTEGER,
+    lane_id INTEGER,
+    session_id TEXT,
+    source TEXT,
+    market TEXT,
+    url TEXT,
+    snapshot TEXT,
+    files TEXT,
+    size INTEGER,
+    shared INTEGER NOT NULL DEFAULT 0,
+    shared_at TEXT,
+    installs INTEGER NOT NULL DEFAULT 0,
+    created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now')),
+    updated_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
+  );
+  CREATE INDEX IF NOT EXISTS idx_artifacts_owner ON artifacts(owner_id, kind);
+  CREATE INDEX IF NOT EXISTS idx_artifacts_shared ON artifacts(shared, kind);
+  CREATE INDEX IF NOT EXISTS idx_artifacts_session ON artifacts(session_id);
+`);
+
 // Seed lane_stage_events from the snapshots that predate it, so upgrading does
 // not read as "every pipeline has never run". Each lane's live `stages` blob
 // becomes one run; each archived feature becomes one more. That is all the