feat: v2.6.0 — Chat UI composer (+ menu, project files, activity panel, permission mode, Stop), git on a workspace's extra folders (#70), long paste as a file (#68), S3 server mode (experimental)

Chat UI:
- Each Claude/Codex session keeps its own chat/terminal view; Settings only
  sets how new sessions open.
- Composer + menu: upload, project files and folders (#54, also dragged from
  the Files/Changes tree), context files, recent uploads, skills, plugins.
- Activity side panel (progress, outputs, files read, uploads, memory,
  skills, connectors) with a file preview; edited-file counts per turn.
- Permission-mode chip (Shift+Tab steps, read back from the pane:
  server/lib/pane-mode.js, GET|POST /api/run/:id/permission-mode).
- Stop (Esc) while the main agent works; the status is checked per agent
  (with session_id /api/agents ignores its status filter) and re-read every
  5 s while Stop shows.
- Dropped images shown in the conversation (GET /api/run/drop/:name, the
  requester's own drop dir), full-size viewer.
- A plain-text paste over 5,000 characters is attached as pasted-text.txt,
  so no prompt reaches tmux/argv limits (#68).

Changes panel: every /api/lanes/:id/git* route takes ?source=<lane_sources
id> (sourceFolder; ENOSOURCE otherwise) and a folder picker switches the
whole panel to a workspace's extra folder (#70).

Server mode S3 (one Linux user per account) — experimental, verified with
fake sudo plus a P6 managed-settings spike on a test account:
- member tmux listing runs in the background (cached, 15 s => unknown);
- transcript snapshot copy is async, chunked, temp file + rename;
- Express Layer patch only on Express 4;
- tmux capturePane/sendKey go to the member's own server.

Docs: the multi-user design moved in as docs/plans/server-mode/README.md
(the AgentHub-Server repo is gone); S3-PLAN P6 result; LANES/API/openapi.

server/__tests__/transcript-sender.test.js

@@ -18,7 +18,7 @@ const fs = require("node:fs");
 const TEST_DB = path.join(os.tmpdir(), `transcript-sender-${Date.now()}-${process.pid}.db`);
 process.env.DASHBOARD_DB_PATH = TEST_DB;
 
-const { classifyTranscriptSender } = require("../routes/sessions");
+const { classifyTranscriptSender, patchCounts } = require("../routes/sessions");
 const { db } = require("../db");
 
 after(() => {
@@ -136,3 +136,35 @@ describe("classifyTranscriptSender — subagent transcript", () => {
     assert.equal(classifyTranscriptSender(assistant(), true), "assistant");
   });
 });
+
+describe("patchCounts — the +/- lines of a Write/Edit result", () => {
+  it("counts a structuredPatch's added and removed lines, not its context", () => {
+    const r = {
+      filePath: "/w/a.ts",
+      structuredPatch: [
+        {
+          oldStart: 1,
+          oldLines: 3,
+          newStart: 1,
+          newLines: 4,
+          lines: [" a", "-b", "+c", "+d", " e"],
+        },
+        { oldStart: 9, oldLines: 1, newStart: 10, newLines: 0, lines: ["-z"] },
+      ],
+    };
+    assert.deepEqual(patchCounts(r), { added: 2, removed: 2 });
+  });
+
+  it("counts a created file's lines as added", () => {
+    assert.deepEqual(patchCounts({ type: "create", content: "a\nb\nc\n", structuredPatch: [] }), {
+      added: 3,
+      removed: 0,
+    });
+  });
+
+  it("answers null for a result that is no edit", () => {
+    assert.equal(patchCounts({ stdout: "ok" }), null);
+    assert.equal(patchCounts("text"), null);
+    assert.equal(patchCounts(undefined), null);
+  });
+});