fix(backend): unblock orchestrator dry-run end-to-end (canonical model + SDK auth) (#13180)

### Why / What / How

**Why:** Two follow-ups landed after PR #13177 deployed and the user
exercised the orchestrator dry-run on dev-builder.

1. **JSON Schema validation gap.** #13177 taught `LlmModel._missing_` to
resolve `anthropic/claude-haiku-4-5` → `CLAUDE_4_5_HAIKU`. That fixed
Pydantic, but `OrchestratorBlock.Input` is validated by `validate_data`
→ `jsonschema.validate` *first*, against a schema whose `enum` is the
literal list of `LlmModel.value` strings. The alias map is a Python
runtime hook — it does not surface in the generated JSON Schema. So the
OR-slug was rejected with `'anthropic/claude-haiku-4-5' is not one of
[...]`.

2. **SDK auth: empty `x-api-key`.** Once jsonschema started passing,
execution reached the EXTENDED_THINKING SDK path in
[orchestrator.py:1670-1674](autogpt_platform/backend/backend/blocks/orchestrator.py#L1670).
That code sets `sdk_env["ANTHROPIC_API_KEY"] = ""` to "force the CLI to
use AUTH_TOKEN." But the Claude Agent SDK merges `options.env` on top of
`os.environ`
([subprocess_cli.py:402](file:claude_agent_sdk/_internal/transport/subprocess_cli.py#L402)),
so the spawned CLI sees `ANTHROPIC_API_KEY=` (present-but-empty) and
emits `x-api-key:` (empty header) on the wire. OpenRouter returns `401
invalid x-api-key`. This bug was latent until #13177 — every
orchestrator dry-run died at jsonschema before reaching the auth wiring.

**What:**
- `simulator.py`: translate the configured simulator model to its
canonical `LlmModel.value` via `LlmModel(_simulator_model()).value`
before injecting into `input["model"]`. The OR-slug default
(`anthropic/claude-haiku-4-5`) becomes `claude-haiku-4-5-20251001` —
which IS in the JSON Schema enum — so `validate_data` passes. Downstream
OpenRouter's Anthropic-compat endpoint accepts both forms, so no further
translation is needed.
- `orchestrator.py`: in the `provider == "open_router"` SDK branch, set
`ANTHROPIC_API_KEY` to the same OpenRouter key (instead of `""`).
OpenRouter accepts either `x-api-key` or `Authorization: Bearer` with
the OR key, so whichever the CLI sends is valid. Explicit set (not
omission) is required because the SDK's merge would otherwise let an
inherited platform `ANTHROPIC_API_KEY` leak through.
- `simulator_test.py`: strengthen
`test_orchestrator_uses_simulation_model` to assert the injected model
is in `{m.value for m in LlmModel}`; add
`test_orchestrator_input_passes_jsonschema_validation` that calls
`validate_data` on `prepare_dry_run`'s output (locks in the exact
regression the user hit).

**How:**

End-to-end proof for the model translation, against real OpenRouter
(4-step script):

```
=== Step 1: reproduce the bug with the OR slug ===
✓ validate_data REJECTS 'anthropic/claude-haiku-4-5' as expected
  'anthropic/claude-haiku-4-5' is not one of ['o3-mini', ...]…

=== Step 2: canonical snapshot passes validate_data + Pydantic ===
✓ validate_data accepts the canonical value
✓ Pydantic resolves Input.model to LlmModel.CLAUDE_4_5_HAIKU

=== Step 3: prepare_dry_run shape after canonical-model fix ===
  prepare_dry_run produced model='anthropic/claude-haiku-4-5'
  Canonical-translated model='claude-haiku-4-5-20251001'
✓ dry-run input (post-fix) passes validate_data

=== Step 4: real LLM call via OpenRouter Anthropic-compat ===
✓ Real LLM call succeeded with canonical snapshot ID
```

The SDK auth fix is supported by the user-reported 401 + the SDK-source
trace
([subprocess_cli.py:402](file:claude_agent_sdk/_internal/transport/subprocess_cli.py#L402)
merges options.env on top of os.environ; setting "" leaves the key set
rather than unset).

### Changes 🏗️

- `prepare_dry_run` translates the simulator model to canonical
`LlmModel.value`.
- Orchestrator's SDK env now uses the OR key for both
`ANTHROPIC_AUTH_TOKEN` and `ANTHROPIC_API_KEY` (was empty string).
- Two strengthened/new tests pin the canonical-value invariant and
jsonschema validation outcome.

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
- [x] `poetry run pytest
backend/executor/simulator_test.py::TestPrepareDryRun
backend/executor/simulator_test.py::TestDefaultSimulatorModel
backend/copilot/tools/test_dry_run.py::test_prepare_dry_run_orchestrator_block
backend/blocks/test/test_llm.py::TestLlmModelMissingHandler` — all green
- [x] End-to-end validation against real OpenRouter — all 4 steps pass
(see "How")
- [x] User-reported 401 on dev-builder traced to the orchestrator SDK
env-var; root cause + SDK-source line cited
- [x] `poetry run black` + `poetry run ruff check` clean on changed
files

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>