CLI: --strict, and a warnings array in result.json (#14601)

# Description

Add `--strict` for CI and scripted pipelines, and a structured
`warnings`
array in `result.json`.

## `--strict`

A NON_CRITICAL slicing warning is logged and the slice succeeds: return
code
`0`, G-code written. That suits interactive use, but a pipeline then
ships a
slice with a warning nobody saw. With `--strict`, such a warning fails
the run
with `CLI_SLICING_ERROR` before the G-code is exported. Without the
flag,
nothing changes.

In FFF the warning that reaches this path is "support needed but
disabled"
(`PrintObject::generate_support_material`). `--no-check` skips that
check, so
`--strict --no-check` is rejected with `CLI_INVALID_PARAMS`.

`--strict` is read before any work, so it doesn't depend on argument
order and
`result.json` reports it for early failures as well.

## `result.json`

Two new top-level fields:

- `warnings`: `[{"class", ...details}]`. One class is wired:
`slicing_warning_non_critical` with `plate_id` and `text`, recorded
whenever
such a warning fires, with or without `--strict`. The array also fills
on
  runs that succeed, so `return_code` stays the verdict.
- `strict_mode`: whether `--strict` was on.

`record_exit_reson` writes `result.json` on Linux only, so both fields
exist
only there. The non-zero exit works on every platform.

## Tests

- `tests/fff_print/test_support_material.cpp` (all platforms): an
overhang
sliced with support off raises the NON_CRITICAL support-needed status,
and
  the no-check flag suppresses it.
- `tests/cli/test_cli_strict.sh` (Linux only): runs `orca-slicer`
without
flags, with `--strict`, and with `--strict --no-check`, and checks the
shell
status and `result.json` of each. It runs the built binary, so it
carries the
`RequiresApp` label, which `scripts/run_unit_tests.sh` excludes because
the
  unit-test job only receives `build/tests`. Run it with
  `ctest --test-dir build/tests -C Release -L RequiresApp`.
- CI: `unit_tests.yml` now passes `Release` on Linux too.
`build_linux.sh`
configures Ninja Multi-Config, and without a config ctest drops the
labels of
plain `add_test()` tests, so this test ran as "Not Run" instead of being
excluded. The docs that assumed Linux was single-config are corrected
too.

Built and run locally on Linux (GCC 14) on current `main`: both tests
pass,
and the touched files compile clean under Clang with `-Werror`.

src/libslic3r/PrintConfig.cpp

@@ -11923,6 +11923,19 @@ CLIActionsConfigDef::CLIActionsConfigDef()
     def->tooltip = L("Do not run any validity checks, such as G-code path conflicts check.");
     def->set_default_value(new ConfigOptionBool(false));
 
+    // --strict turns the non-critical slicing warnings the CLI otherwise only logs into a
+    // failed run, and records strict_mode in result.json so consumers can tell the modes apart.
+    def = this->add("strict", coBool);
+    def->label = L("Strict mode");
+    def->tooltip = L("Exit non-zero when slicing raises a non-critical warning that is "
+                     "otherwise only logged, such as a model that needs support while "
+                     "support is disabled. Use this in CI or scripted pipelines that should "
+                     "never ship a subtly broken slice. Each such warning is also listed "
+                     "with a stable class in the `warnings` array of result.json, which is "
+                     "written on Linux only. Cannot be combined with --no-check, which skips "
+                     "the support check.");
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("normative_check", coBool);
     def->label = L("Normative check");
     def->tooltip = L("Check the normative items.");