feat(workspace): AI tool per session, one place to start a session, ended sessions open like Claude Desktop

- A session picks its own AI tool: `tool` on POST /api/lanes/:id/start
  (a catalog id, known + enabled, else 400 EBADTOOL/EDISABLED); a resume
  keeps the tool its session ran on (`sessions.tool`). The workspace's
  `lanes.tool` is now only the default.
- The workspace home's prompt box is the one place a session starts. Its
  fields run in order: AI → AI Router (Native or a profile) → Model (the
  tool's own list, or the router's models) → Permission (Claude mode /
  Codex sandbox+approval / catalog bypass) → Effort.
- The pane's run form (RunSetup) is gone: New run, a single pane's exit and
  an empty split pane's New session all go to the home. RunSetup.tsx keeps
  PromptEditor, CwdAutocomplete and ModelPicker (new `choices` prop).
- The tool icon moved from the sidebar's workspace row to each session row
  (right edge, `session.tool`); the split-pane header shows the run's tool.
- An ended session opens in its workspace (`&session=`, SessionReplay.tsx):
  its conversation read-only plus a prompt box; only a SENT message resumes
  it (resumeSessionId + prompt, first free slot). The console is only
  hidden behind it.
- Analyst button beside Files/Changes in the right panel opens
  /sessions/:id for the opened session.
- Gemini CLI ships its own icon (client/public/ai-tools/gemini.svg, from
  zonalogo.com).
- RouterPicker always shows (Native disabled for tools without router
  support); useAiRouters() exported.
- Tests: server start-with-tool cases; SessionReplay, home field order/tool/
  router models, empty pane, Analyst; dropped the cwd-field suites
  (Run.defaultCwd, Workspace.laneCwd). Docs: CLAUDE.md rules, API.md,
  LANES.md, README, ARCHITECTURE, INSTALL.

client/src/components/lanes/WorkspaceSessionList.tsx

@@ -3,15 +3,16 @@
  * sidebar: the ones the workspace OWNS and has not archived
  * (`GET /api/sessions?lane=<id>&archived=0`, newest first) — never the other
  * sessions that ran in its folder. A row's dot
- * shows its state (`sessionDot`: live pane, needs you, error); double-click
+ * shows its state (`sessionDot`: live pane, needs you, error) and its right
+ * edge the AI tool the session ran on (`sessions.tool`); double-click
  * renames it and its hover button archives it (`PATCH {name}` / `{archived}`,
  * which deletes nothing). A session with a LIVE pane (a `GET /api/run` handle
  * carrying its session id) opens that tmux pane on the Workspace page
  * (`?lane=<id>&run=<runId>`, Ctrl/Cmd+click `&pane=1` to open it in a second
  * split pane) — attaching, never starting or resuming anything;
- * any other session opens its read-only transcript (`/sessions/:id`), where
- * Resume is a separate, explicit action, because a resume re-reads the whole
- * transcript into context.
+ * any other session opens in its workspace too (`?lane=<id>&session=<id>`,
+ * `SessionReplay`): its conversation with a prompt box, resumed only when a
+ * message is SENT, because a resume re-reads the whole transcript into context.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
@@ -23,6 +24,8 @@ import { api, type RunHandle } from "../../lib/api";
 import { isSessionAwaitingInput, type Lane, type Session } from "../../lib/types";
 import { timeAgo } from "../../lib/format";
 import { ConfirmModal } from "../ConfirmModal";
+import { AiToolIcon } from "../AiToolIcon";
+import { useAiTools } from "../../hooks/useAiTools";
 
 export const SESSION_LIMIT = 20;
 
@@ -164,6 +167,7 @@ export function WorkspaceSessionList({
   liveRuns,
   query,
   selectedRunId,
+  selectedSessionId = null,
   onMatches,
   hidden = false,
 }: {
@@ -174,6 +178,8 @@ export function WorkspaceSessionList({
   query: string;
   /** The `run` the Workspace page is attached to, to mark its row. */
   selectedRunId: string | null;
+  /** The ended session the Workspace page is showing (`session`), likewise. */
+  selectedSessionId?: string | null;
   /** How many sessions match `query`, once they are loaded — lets the
    *  sidebar search find a workspace by a session's name. */
   onMatches?: (count: number) => void;
@@ -182,6 +188,7 @@ export function WorkspaceSessionList({
 }) {
   const { t } = useTranslation("lanes");
   const navigate = useNavigate();
+  const tools = useAiTools();
   // Bumped after a rename or an archive, so the list re-reads.
   const [version, setVersion] = useState(0);
   const [renaming, setRenaming] = useState<string | null>(null);
@@ -276,7 +283,7 @@ export function WorkspaceSessionList({
       <ul data-testid={`workspace-sessions-${lane.id}`} className="space-y-px">
         {shown.map((s) => {
           const run = runFor(s);
-          const selected = !!run && run.id === selectedRunId;
+          const selected = run ? run.id === selectedRunId : s.id === selectedSessionId;
           if (renaming === s.id) {
             return (
               <li key={s.id} className="py-0.5 pl-7 pr-2">
@@ -314,7 +321,7 @@ export function WorkspaceSessionList({
                         `/workspace?lane=${lane.id}&run=${encodeURIComponent(run.id)}${
                           e.ctrlKey || e.metaKey ? "&pane=1" : ""
                         }`
-                      : `/sessions/${s.id}`
+                      : `/workspace?lane=${lane.id}&session=${encodeURIComponent(s.id)}`
                   )
                 }
                 onDoubleClick={() => {
@@ -326,7 +333,7 @@ export function WorkspaceSessionList({
                     ? `\n${t("tree.worktreeSession", { name: sessionWorktreeName(lane, s) })}`
                     : ""
                 }\n${run ? t("tree.splitHint") : t("tree.transcriptHint")}`}
-                className={`flex w-full items-center gap-2 rounded-md py-1 pl-7 pr-7 text-left text-[12px] ${
+                className={`flex w-full items-center gap-2 rounded-md py-1 pl-7 pr-2 text-left text-[12px] ${
                   selected
                     ? "bg-accent/10 text-fg-primary"
                     : "text-fg-secondary hover:bg-surface-3 hover:text-fg-primary"
@@ -344,6 +351,10 @@ export function WorkspaceSessionList({
                     className="h-3 w-3 shrink-0 text-fg-muted"
                   />
                 )}
+                <AiToolIcon
+                  tool={{ id: s.tool || "claude", label: tools.label(s.tool || "claude") }}
+                  className="ml-auto h-3.5 w-3.5 shrink-0 !p-0 opacity-70 group-hover:invisible"
+                />
               </button>
               <button
                 type="button"