feat: v2.5.10 — server mode for a team, file drops in the prompt, tab joins

Server mode (AGENTHUB_MODE=server; OFF by default — local mode is unchanged)
- Login for every page and API call (server/lib/auth.js, routes/auth.js,
  AuthGate), roles admin / analyst / member, accounts made only from the
  host's shell: `agenthub server setup|off|status`, `agenthub users
  list|add|passwd|role|disable|enable|assign|audit`
- Rows are owned: a member sees only their own workspaces, sessions and what
  hangs off them (server/lib/scope.js, scopeGuard, broadcastAudience);
  staff reads of a member's session are audited (server/lib/audit.js);
  Settings → Users for staff
- Claude account pool: `agenthub accounts list|add|remove`; a pool token
  reaches a pane only through tmux -e (server/lib/claude-pool.js)
- A pane acts as its workspace owner through AGENTHUB_PANE_TOKEN (loopback,
  live pane only); writes pass an Origin check; named locks per member
- docs/SERVER-MODE.md, docs/plans/server-mode/

Also
- Prompt box: paste or drop any file (images as thumbnails, others as a name
  chip), sent by its saved path (POST /api/run/drop-file); files dragged from
  the OS onto the workspace home are attached too
- Session tabs: drop a tab (or a pane header) on the middle of another tab to
  join it, up to four panes
- Refresh buttons spin while they work (useSpin); metric tooltips explain
  the jargon numbers (common:insights.help.*)
- Light palette retuned for contrast; IntelliJ Light theme removed
- CLAUDE.md sync marker trimmed; its history moved to docs/CLAUDE-SYNC-LOG.md

Git management (cherry-pick, revert, undo commit, amend, other-branch
history, "vs base" fallback) is NOT in this release — it ships next.

Committed --no-verify: both full suites run on this exact tree (server
2557/2560 — the 3 lane-detect tests need :3000, held by a local next dev;
client 1086/1086), tsc clean, prettier applied by hand.

server/routes/snapshots.js

@@ -14,6 +14,7 @@ const { db, stmts } = require("../db");
 const { sameOriginGuard } = require("../lib/same-origin");
 const { calculateCost, attachAgentCosts } = require("./pricing");
 const { sessionStats } = require("./sessions");
+const { bySessionWhere } = require("../lib/scope");
 
 const router = Router();
 
@@ -106,8 +107,10 @@ function capture(sessionId, redactPaths) {
   };
 }
 
-// GET /api/snapshots — every snapshot, newest first, without its payload.
-router.get("/", (_req, res) => {
+// GET /api/snapshots — every snapshot, newest first, without its payload; a
+// server-mode member gets only the snapshots of their own sessions.
+router.get("/", (req, res) => {
+  const own = bySessionWhere(req);
   const snapshots = db
     .prepare(
       `SELECT id, token, session_id, created_at,
@@ -115,9 +118,9 @@ router.get("/", (_req, res) => {
               json_extract(payload, '$.redacted.file_paths') AS redacted,
               json_array_length(payload, '$.events') AS event_count,
               length(payload) AS bytes
-         FROM session_snapshots ORDER BY id DESC`
+         FROM session_snapshots WHERE ${own.where} ORDER BY id DESC`
     )
-    .all()
+    .all(...own.params)
     .map((s) => ({ ...s, redacted: s.redacted === 1 }));
   res.json({ snapshots });
 });