fix(cli): reject default-surface flags leaked onto the web subcommand

ds-review-bot: `dsh web -p task`, `dsh web --resume s`, and `dsh --config c.yml
web` reached the web action with those values in program.opts() but the action
ignored them and served — silently dropping mode-specific inputs. The web
action now reads the parent opts and fails loud (exit 1) on a leaked
--config/-p/--resume, matching the root mode's mixing guard. Covered in
args.spec.ts.

Also (ds-review-bot): tui-demo/README documented the removed `dsh
[path-to-cordis.yml]` positional form; corrected to bare `dsh` / `dsh --config
<path>`. Agent Note + Chinese pair note the web-leak guard.

apps/cli/tests/args.spec.ts

@@ -47,6 +47,11 @@ describe('parseDshArgs', () => {
     expect(exitCode(['-p', 'x', '--resume', 's'])).toBe(1)
     expect(exitCode(['--bogus'])).toBe(1)
     expect(exitCode(['bogus-positional'])).toBe(1)
+    // A default-surface flag on either side of `web` leaks into program.opts()
+    // but the web subcommand shares none of them: reject rather than serve.
+    expect(exitCode(['web', '-p', 'task'])).toBe(1)
+    expect(exitCode(['web', '--resume', 's'])).toBe(1)
+    expect(exitCode(['--config', 'c.yml', 'web'])).toBe(1)
   })
 
   it('exits 0 for --help (disclosing web) and --version', () => {