feat: echter Download-Fortschritt via Datei-Polling

`hf` gibt im Nicht-TTY-Modus keinen Fortschritt aus (am Bosgame verifiziert:
0 CR-Frames). Stattdessen pollt jobengine.attach_download_progress die
wachsende <local-dir>/.cache/huggingface/download/*.incomplete-Datei gegen die
Gesamtgroesse aus der HF-Tree-API (cookbook.hf_file_size) -> exaktes %.

- attach_download_progress an /api/download, install-recipe, install-model
- Frontend (Aktivitaet + Server-Karte): nutzt job.progress bevorzugt,
  Log-%-Parsing bleibt Fallback fuer Tools, die selbst Prozente ausgeben

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

routers/models.py

@@ -15,7 +15,8 @@ from ruamel.yaml.scalarstring import LiteralScalarString
 from auth import auth
 from config import (CMD_TEMPLATE, CONFIG_PATH, DEFAULT_TTL, HF_DOWNLOAD_ENV, LLAMA_SWAP_URL,
                    MODELS_DIR, TOKEN, hf_bin)
-from jobengine import JOBS, start_job
+from jobengine import JOBS, start_job, attach_download_progress
+from routers.cookbook import hf_file_size
 from llamaswap import _swap_get, read_config, write_config
 from hw_math import extract_params_b, max_ctx_for, estimate_memory_gb
 import re
@@ -146,6 +147,7 @@ def download(req: DownloadReq):
         env["HF_TOKEN"] = req.hf_token
     job_id = start_job(args, f"download {req.repo}/{req.file}", env=env)
     JOBS[job_id]["result_path"] = str(target / req.file)
+    attach_download_progress(job_id, str(target), hf_file_size(req.repo, req.file))
     return {"job_id": job_id, "expected_path": str(target / req.file)}