[fix] nopy: spawn the pyinfra argv, never a shell string

Closes DOCS-AUDIT §4.2 (point 3, the last one open) and §1.3.

`executeCall` joined `DeployCall.command` and ran it through
`execa({shell: true})`, which made every value on that command line shell
syntax. The finding framed it as a quoting problem "in the password"; it was
wider than that. `--data` values were interpolated inside double quotes, so a
backtick or a `$(…)` in *any* variable value was command substitution and a `;`
ended the command and began another.

`buildDeployCall` now emits a true argv — one element per argument, nothing
pre-quoted — and the executor spawns `execa(command[0], command.slice(1))` with
no `shell` option at all. pyinfra is still found on PATH and stdio stays
inherited, so live output is unchanged.

`maskCommand()` walks the argv by position instead of pattern-matching a joined
string, which closes a leak of its own: it used to bound a secret's value on the
closing `"` the builder had written two modules away, so a value containing a
`"` leaked its own tail. It is now the only thing that turns the command back
into a string, for display, and it shell-quotes as it goes so `--print-only`
output stays pasteable.

Also in `buildDeployCall`: `logConfigToFlags()` finally has a caller (§1.3). It
was exported and unit-tested with nothing consuming it, so `log.verbosity` and
`log.debug` in `.nopyrc.json` did nothing at all. The flags are prefixed onto
the argv right after `-y`. Consequence worth knowing rather than discovering:
`packages/nopy/.nopyrc.json` has always asked for `"verbosity": "trace",
"debug": true`, so a run from that directory now really does get `-vvv --debug`.

The tests move with it — the mock is `execa(file, args, opts)` with no factory
to unwrap, and the new cases are the ones that would have caught this: an argv
element holding `$(id); rm -rf /` stays one element, a secret whose value
contains a quote is masked whole, and `execa` is asserted never to be asked for
a shell.

What remains is not fixable here: the value still reaches pyinfra on its command
line, so it is visible in `ps`. That is pyinfra's `--data` interface.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DCzYTAm9QUhvLNr2EpdagJ

packages/nopy/tests/executor.execute.test.ts

@@ -1,9 +1,9 @@
 /**
  * Tests for the executeDeployCalls path of nopy.executor.
  *
- * execa is mocked so no pyinfra process is ever spawned. Note the shape:
- * the module calls execa({ shell: true })(command, opts), so the mock is a
- * factory returning the runner.
+ * execa is mocked so no pyinfra process is ever spawned. The module calls
+ * `execa(file, args, opts)` directly — no shell, so no factory call to unwrap
+ * as there was while it went through `execa({ shell: true })`.
  */
 
 import { beforeEach, describe, expect, it, vi } from 'vitest';
@@ -11,7 +11,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 const runner = vi.fn();
 
 vi.mock('execa', () => ({
-  execa: vi.fn(() => runner),
+  execa: vi.fn((...args: unknown[]) => runner(...args)),
 }));
 
 import { execa } from 'execa';
@@ -50,16 +50,27 @@ describe('executeDeployCalls', () => {
     logSpy.mockRestore();
   });
 
-  it('runs the joined command in the call cwd with inherited stdio', async () => {
+  it('spawns the argv directly in the call cwd with inherited stdio', async () => {
     await executeDeployCalls([call('cube-a')]);
 
-    expect(execa).toHaveBeenCalledWith({ shell: true });
-    expect(runner).toHaveBeenCalledWith('pyinfra web-1 -y cube-a.deploy.py', {
+    expect(execa).toHaveBeenCalledWith('pyinfra', ['web-1', '-y', 'cube-a.deploy.py'], {
       cwd: '/cubes/cube-a',
       stdio: 'inherit',
     });
   });
 
+  it('never asks execa for a shell', async () => {
+    // The regression that matters: with `shell: true` every `--data` value was
+    // shell syntax, so a password or a variable containing `;` or `$(…)` ran.
+    await executeDeployCalls([
+      { ...call('cube-a'), command: ['pyinfra', 'web-1', '--data', 'MOTD=$(id); rm -rf /'] },
+    ]);
+
+    const [, , options] = vi.mocked(execa).mock.calls[0] as unknown[];
+    expect(options).not.toHaveProperty('shell');
+    expect(vi.mocked(execa).mock.calls[0][1]).toContain('MOTD=$(id); rm -rf /');
+  });
+
   it('reports success with a non-negative duration', async () => {
     const [result] = await executeDeployCalls([call('cube-a')]);