test(peer-cli): cover solid streamed installs

NEXT_STEPS item 3 needed solid archive handling to be a deliberate
contract instead of an incidental RAR header attribute. Add a tiny real
solid RAR fixture and S41 to the extended peer-cli scenarios so the
Docker harness proves this path end to end.

The scenario verifies the source archive with container-bundled
`unrar lt`, streams the install with the injected provider, and then
asserts the receiver is installed local-only without a root archive or
root `version.ini`. It also compares local payload SHA-256 hashes against
`unrar p` output and checks the streamed byte count matches the extracted
entries. This keeps the existing one metadata pass plus one sequential
payload pass contract covered for solid archives.

Test Plan:
- just fmt
- just test
- python3 -m py_compile crates/lanspread-peer-cli/scripts/run_extended_scenarios.py
- python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S41 --build-image
- python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S41
- git diff --check
- git diff --cached --check

Refs: NEXT_STEPS.md item 3

crates/lanspread-peer-cli/fixtures/fixture-solid/cnctw/version.ini

@@ -0,0 +1 @@
+20160128

crates/lanspread-peer-cli/scripts/run_extended_scenarios.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Run the peer-cli scenarios S1-S40 through Docker."""
+"""Run the peer-cli scenarios S1-S41 through Docker."""
 
 from __future__ import annotations
 
@@ -328,6 +328,7 @@ class Runner:
             ("S37", self.s37_single_source_download_throughput),
             ("S39", self.s39_streamed_install_local_only),
             ("S40", self.s40_streamed_receiver_not_source),
+            ("S41", self.s41_solid_archive_streamed_install),
         ]
 
         for scenario_id, scenario in scenarios:
@@ -1171,6 +1172,84 @@ class Runner:
             f"and download errored '{err['error']}'"
         )
 
+    def s41_solid_archive_streamed_install(self) -> str:
+        source_dir = self.fixture_root / "s41-solid-source"
+        source_game = source_dir / "cnctw"
+        shutil.copytree(FIXTURES / "fixture-solid" / "cnctw", source_game)
+
+        source = self.peer("s41-solid-source", games_dir=source_dir)
+        assert_peer_rar_archive_solid(source, "cnctw")
+        client = self.peer("s41-solid-client")
+        connect_many(client, [source])
+        wait_remote_game(client, "cnctw", peer_count=1, version="20160128")
+
+        waiter = LineWaiter(len(client.output))
+        client.send({"cmd": "stream-install", "game_id": "cnctw"})
+        client.wait_for(
+            event_is("got-game-files", "cnctw"),
+            timeout=20,
+            description="got solid cnctw files",
+            waiter=waiter,
+        )
+        client.wait_for(
+            event_is("download-finished", "cnctw"),
+            timeout=60,
+            description="solid stream finish cnctw",
+            waiter=waiter,
+        )
+        client.wait_for(
+            event_is("install-finished", "cnctw"),
+            timeout=30,
+            description="solid stream install cnctw",
+            waiter=waiter,
+        )
+
+        game = wait_local_game(client, "cnctw", downloaded=False, installed=True)
+        assert_game_state(
+            game,
+            downloaded=False,
+            installed=True,
+            availability="LocalOnly",
+        )
+        game_root = client.host_games_dir / "cnctw"
+        assert_not_exists(game_root / "version.ini")
+        assert_not_exists(game_root / "cnctw.eti")
+
+        expected = {
+            "bin/cnctw-solid-payload.bin": unrar_entry_sha256(
+                source, "cnctw", "bin/cnctw-solid-payload.bin"
+            ),
+            "data/cnctw-solid-assets.dat": unrar_entry_sha256(
+                source, "cnctw", "data/cnctw-solid-assets.dat"
+            ),
+        }
+        actual = {
+            rel: sha256_file(game_root / "local" / rel)
+            for rel in expected
+        }
+        if actual != expected:
+            raise ScenarioError(
+                f"solid streamed payload hashes mismatched: {actual} != {expected}"
+            )
+
+        streamed_bytes = sum(
+            int(item.get("data", {}).get("length", 0))
+            for item in client.output
+            if item.get("type") == "event"
+            and item.get("event") == "download-chunk-finished"
+            and item.get("data", {}).get("game_id") == "cnctw"
+        )
+        expected_bytes = sum((game_root / "local" / rel).stat().st_size for rel in expected)
+        if streamed_bytes != expected_bytes:
+            raise ScenarioError(
+                f"solid streamed byte count mismatch: {streamed_bytes} != {expected_bytes}"
+            )
+
+        return (
+            "solid cnctw archive streamed through one local-only install; "
+            f"payload hashes={actual}, bytes={streamed_bytes}"
+        )
+
 
 def run(command: list[str], description: str) -> subprocess.CompletedProcess[str]:
     result = subprocess.run(
@@ -1307,6 +1386,22 @@ def unrar_entry_sha256(peer: Peer, game_id: str, relative_path: str) -> str:
     return output.split()[0]
 
 
+def assert_peer_rar_archive_solid(peer: Peer, game_id: str) -> None:
+    output = peer.docker_exec(
+        "unrar",
+        "lt",
+        "-cfg-",
+        f"/games/{game_id}/{game_id}.eti",
+    ).stdout
+    for line in output.splitlines():
+        stripped = line.strip()
+        if stripped.startswith("Details:"):
+            if "solid" in stripped.lower():
+                return
+            raise ScenarioError(f"RAR archive is not solid: {game_id}")
+    raise ScenarioError(f"RAR archive details were not reported: {game_id}")
+
+
 def format_bytes(size: int) -> str:
     return f"{size / 1024 / 1024 / 1024:.2f} GiB"