feat(multiuser): phase 3, ownership threading + scoping

Threads per-user ownership through sessions, cases, cron, and the permission
policy. All scoping is a no-op in single-user mode (isMultiUserMode() guards).

Sessions
- Session.owner stamped at every create path from req.authUser / job.owner:
  POST /api/sessions, /api/run, /api/quick-start, ralph start, cron launch,
  plan generation. Round-trips through recovery (MuxSession.owner mirror, read
  muxSession.owner ?? savedState?.owner) and the mux layer.
- findSessionOrFail(ctx, id, req) now does a NOT_FOUND owner check (never 403, so
  other users' session existence is not leaked); wired at ~50 call sites.
- List endpoints filtered by owner: GET /api/sessions, /api/sessions/unified
  (live+persisted+lifecycle scoped, host-wide transcripts admin-only), cron jobs.

Permission policy (section 6.3)
- resolveClaudeModeForUsername wraps getClaudeModeConfig at every spawn site so a
  non-granted user is forced to --permission-mode auto (bypass -> auto), including
  recovery (or a reboot would un-downgrade). buildPromptArgs now respects the
  session's claudeMode, closing the one-shot (runPrompt) bypass hole.
- Shell mode and cron launchCommand require canBypassPermissions: 403 at
  POST /api/sessions, /api/quick-start create, cron job create, AND cron fire time
  (re-checked against the owner's current grant).

Cases
- resolveCasesDir(user): per-user ~/codeman-users/<name>/cases in multi-user, the
  shared ~/codeman-cases otherwise. All case CRUD + ralph + plan + quick-start
  resolve through it. resolveCasePath is owner-aware.
- GET /api/cases scoped per user (own folders; legacy linked cases admin-only;
  remote/docker cases owner-filtered). RemoteCase/DockerCase gain owner, stamped
  at link/quickcreate/import.
- Remote + Docker host CRUD is admin-only.
- Non-admin workingDir confinement (the linchpin): realpath must resolve inside the
  user's space, enforced at POST /api/sessions and /api/run BEFORE any disk write.

Limits
- sessionCapacityState / sessionCapacityMessage centralize the global + per-user
  cap (CODEMAN_MAX_SESSIONS_PER_USER, default global/2), replacing the 6 copy-pasted
  MAX_CONCURRENT_SESSIONS checks.

Tests: test/ownership-scoping.test.ts (case isolation, host-CRUD gate, workingDir +
shell gates, and the scoping helpers). Deferred to phase 4: WS owner gate, SSE
fan-out filtering, file-route preview/thumbnail helper scoping, push routing.

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

src/web/server.ts

@@ -136,7 +136,7 @@ import { getLatestPlanUsage } from './plan-usage-latest.js';
 import type { ScheduledRun } from './ports/index.js';
 import { registerAuthMiddleware, registerSecurityHeaders, registerHostGuard } from './middleware/auth.js';
 import { isMultiUserMode } from '../config/multiuser.js';
-import { bootstrapInitialAdmin, hasUsers } from '../user-store.js';
+import { bootstrapInitialAdmin, hasUsers, resolveClaudeModeForUsername } from '../user-store.js';
 import { installRouteErrorHandler } from './route-error-handler.js';
 import { isExplicitlyEnabled, isLoopbackBindHost, buildHostPolicy, type HostPolicy } from './network-auth-policy.js';
 import {
@@ -2238,7 +2238,16 @@ export class WebServer extends EventEmitter {
             const sessionName = savedState?.name || muxSession.name || muxSession.muxName;
 
             // Create a session object for this mux session
-            const recoveryClaudeMode = await this.getClaudeModeConfig();
+            // Owner round-trips like remote/docker: mux-sessions.json carries
+            // MuxSession.owner, state.json carries SessionState.owner. Recovery must
+            // re-resolve the permission mode with the RECOVERED owner or a reboot
+            // would silently un-downgrade a non-granted user's restored session.
+            const recoveredOwner = muxSession.owner ?? savedState?.owner;
+            const recoveryClaudeModeConfig = await this.getClaudeModeConfig();
+            const recoveryClaudeMode = {
+              claudeMode: await resolveClaudeModeForUsername(recoveryClaudeModeConfig.claudeMode, recoveredOwner),
+              allowedTools: recoveryClaudeModeConfig.allowedTools,
+            };
             // Recover envOverrides from the internal __envOverrides field written by
             // session-manager (see updateSessionState). Cast to read the non-public field.
             // Note: a legacy CLAUDE_CODE_EFFORT_LEVEL entry is auto-migrated to `effort`
@@ -2275,6 +2284,7 @@ export class WebServer extends EventEmitter {
               // MuxSession.docker; state.json carries SessionState.docker), so recovery
               // rebuilds the `docker exec` launch instead of a broken local command.
               docker: muxSession.docker ?? savedState?.docker,
+              owner: recoveredOwner,
             });
 
             // Update session name if it was a "Restored:" placeholder or doesn't match saved name