Enhance CLI and documentation for capturing VM inventory

- Introduced new `capture` commands in the CLI to allow users to merge VM inventory into local manifests without downloading weights.
- Updated `README.md` and `cli.md` to include detailed instructions for the new capture functionality, including options for models and extensions.
- Enhanced `decisions.md` to clarify the role of captured links in the manifest files.
- Improved `extensions.md` to document the process of capturing installed extensions back to the local configuration.
- Added new functions in `civitai.py` to support fetching model versions by hash and generating canonical URLs for models.

src/gpu_rent/civitai.py

@@ -92,7 +92,8 @@ def fetch_model_version(token: str, host: str, version_id: int, timeout: float =
         url = f"https://{candidate}/api/v1/model-versions/{version_id}"
         try:
             with httpx.Client(timeout=timeout, follow_redirects=True) as client:
-                response = client.get(url, headers={"Authorization": f"Bearer {token}"})
+                headers = {"Authorization": f"Bearer {token}"} if token else {}
+                response = client.get(url, headers=headers)
         except httpx.HTTPError as exc:
             last_error = str(exc)
             continue
@@ -106,3 +107,67 @@ def fetch_model_version(token: str, host: str, version_id: int, timeout: float =
         if response.status_code not in {404, 400}:
             break
     raise CloudError(f"Civitai version {version_id}: {last_error} (хосты {', '.join(seen)})")
+
+
+def fetch_model_version_by_hash(
+    token: str | None,
+    host: str,
+    sha256: str,
+    timeout: float = 30.0,
+) -> tuple[str, dict]:
+    """GET /api/v1/model-versions/by-hash/{sha}; public, token optional for NSFW/region."""
+    digest = sha256.strip().lower()
+    if len(digest) != 64 or any(c not in "0123456789abcdef" for c in digest):
+        raise CloudError(f"Civitai by-hash: неверный SHA256 ({sha256[:16]}…)")
+    first = _normalize_host(host)
+    order = [first, other_host(first)]
+    last_error = "нет ответа"
+    seen: set[str] = set()
+    headers = {"Authorization": f"Bearer {token}"} if token else {}
+    for candidate in order:
+        if candidate in seen or candidate not in ALLOWED_HOSTS:
+            continue
+        seen.add(candidate)
+        url = f"https://{candidate}/api/v1/model-versions/by-hash/{digest}"
+        try:
+            with httpx.Client(timeout=timeout, follow_redirects=True) as client:
+                response = client.get(url, headers=headers)
+        except httpx.HTTPError as exc:
+            last_error = str(exc)
+            continue
+        if response.status_code == 200:
+            data = response.json()
+            if isinstance(data, dict) and data.get("id") is not None:
+                return candidate, data
+            last_error = "пустой ответ"
+            continue
+        last_error = f"HTTP {response.status_code}"
+        if response.status_code not in {404, 400}:
+            break
+    raise CloudError(f"Civitai by-hash {digest[:12]}…: {last_error} (хосты {', '.join(seen)})")
+
+
+def civitai_model_url(model_id: int, version_id: int, host: str = "civitai.red") -> str:
+    """Canonical manifest URL (links only — no download)."""
+    h = _normalize_host(host)
+    if h not in ALLOWED_HOSTS:
+        h = "civitai.red"
+    if h == "civitai.green":
+        h = "civitai.com"
+    return f"https://{h}/models/{int(model_id)}?modelVersionId={int(version_id)}"
+
+
+def version_ids_from_payload(version: dict) -> tuple[int | None, int | None]:
+    """Extract (version_id, model_id) from a Civitai version JSON object."""
+    try:
+        vid = int(version["id"]) if version.get("id") is not None else None
+    except (TypeError, ValueError, KeyError):
+        vid = None
+    mid = version.get("modelId")
+    if mid is None and isinstance(version.get("model"), dict):
+        mid = version["model"].get("id")
+    try:
+        model_id = int(mid) if mid is not None else None
+    except (TypeError, ValueError):
+        model_id = None
+    return vid, model_id