test(peer-cli): expand streamed install edge coverage

NEXT_STEPS item 6 called for the remaining streamed-install edge cases to
be covered in the peer-cli matrix. Add S43-S47 for already-installed
rejection, corrupt archive rollback, sender disconnect, receiver cancel,
and sorted multi-archive streaming.

The receiver-cancel scenario needs the harness to drive the same runtime
path as the GUI, so `lanspread-peer-cli` now accepts a narrow
`cancel-download` command that forwards to `PeerCommand::CancelDownload`.
A parser test covers the new JSONL command shape.

Add `fixture-multi/cnctw`, a tiny two-archive RAR fixture. S47 uses it to
prove streamed installs process root `.eti` archives in sorted order and
commit only extracted `local/` payloads, not the root archives or
`version.ini` sentinel.

Test Plan:
- just fmt
- python3 -m py_compile crates/lanspread-peer-cli/scripts/run_extended_scenarios.py
- python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S43 S44 S45 S46 S47 --build-image
- just test
- just clippy
- git diff --check
- git diff --cached --check

Refs: NEXT_STEPS.md item 6

PEER_CLI_SCENARIOS.md

@@ -50,6 +50,11 @@ for deterministic local runs; mDNS/macvlan remains an environment smoke path.
 | S40 | Streamed install receiver is not a peer source | After S39, a third peer connects only to the streamed-install receiver. | The third peer may see the receiver's local-only summary in peer snapshots, but `list-games` remote aggregation does not expose `cnctw` as downloadable, `peer_count` remains zero/absent, and attempting `download cnctw` fails with no local files created. |
 | S41 | Solid archive streamed install | Empty client connects to a peer serving `fixture-solid/cnctw`, whose `.eti` is a real solid RAR archive. The receiver uses the container-bundled `unrar` stream provider. | The fixture is verified as solid with `unrar lt`; streamed install finishes with `downloaded=false`, `installed=true`, `availability=LocalOnly`; root archive and `version.ini` are absent; streamed byte count equals the extracted solid entries; local payload SHA-256 hashes match `unrar p` output. |
 | S42 | Streamed install whole-stream retry | Empty client connects to two peers serving the same catalog-version `cnctw`: one broken source whose `--unrar` path is missing, followed by one good source. | The broken source sorts before the good source in retry order, contributes zero chunks, and the good source completes a fresh whole-stream attempt. The final state is local-only installed, no root archive/sentinel, no `.local.installing`, byte count matches the extracted entries, and payload hashes match the good source. |
+| S43 | Already-installed streamed install rejection | A client first stream-installs `cnctw`, then attempts `stream-install cnctw` again. | The second request emits `download-failed`, does not emit a new success event, leaves the existing local-only install intact, and clears active operations. |
+| S44 | Corrupt archive streamed install rollback | A source advertises catalog-version `cnctw`, but its root `.eti` is replaced with invalid bytes before the client requests `stream-install cnctw`. | The stream emits `download-failed`, does not emit download/install success, clears active operations, and leaves no `local/`, `.local.installing`, root archive, or root `version.ini` on the receiver. |
+| S45 | Sender disconnect during streamed install | A source serves large catalog-version `alienswarm`; after the client receives the first streamed chunk, the source container is killed. | The operation reaches a terminal failure/peers-gone event, emits no download/install success, clears active operations, and rolls back local/staging state. |
+| S46 | Receiver cancel during streamed install | A client starts streaming large catalog-version `alienswarm`, receives the first chunk, then sends `cancel-download alienswarm`. | The receiver cancels without emitting download/install success or a user-visible download failure, clears active operations, and rolls back local/staging state. |
+| S47 | Multi-archive streamed install order | A source serves `fixture-multi/cnctw` with two root `.eti` archives named to require sorted processing. | Streamed chunk paths arrive in root archive sort order, both payloads install under `local/`, the receiver is local-only installed, and no root archives or sentinel are committed. |
 
 ## Version-Skew Contract
 
@@ -133,9 +138,37 @@ Use S39-S41 to pin down low-disk streamed installs:
 - S42 verifies retry/resume semantics: failed streamed attempts roll back their
   staging directory and retry the whole stream from another validated peer.
   There is no byte-offset resume contract.
+- S43-S47 cover the remaining streamed-install failure and archive-shape edges:
+  already-installed rejection, corrupt archive rollback, sender disconnect,
+  receiver cancel, and multi-archive root sorting.
 
 ## Run Log
 
+### 2026-06-07 - Streamed Install Edge Coverage (S43-S47)
+
+- Code under test added `cancel-download` to `lanspread-peer-cli`, added the
+  tiny `fixture-multi/cnctw` two-archive fixture, and added S43-S47 in
+  `run_extended_scenarios.py`.
+- Gates before Docker: `just fmt` and `python3 -m py_compile
+  crates/lanspread-peer-cli/scripts/run_extended_scenarios.py` passed.
+- Runner:
+  `python3 crates/lanspread-peer-cli/scripts/run_extended_scenarios.py S43 S44 S45 S46 S47 --build-image`
+  passed against the rebuilt `lanspread-peer-cli:dev` image.
+- S43 stream-installed `cnctw`, retried `stream-install cnctw`, observed
+  `download-failed`, and verified the existing local-only install stayed intact.
+- S44 replaced the source `cnctw.eti` with invalid bytes. The receiver emitted
+  `download-failed`, cleared active operations, and left no `local/`,
+  `.local.installing`, root archive, or root `version.ini`.
+- S45 killed the sole `alienswarm` source after the first streamed chunk. The
+  receiver ended with `download-failed`, emitted no success, cleared active
+  operations, and rolled back local/staging state.
+- S46 cancelled `alienswarm` on the receiver after the first streamed chunk.
+  The receiver emitted no success and no user-visible `download-failed`, cleared
+  active operations, and rolled back local/staging state.
+- S47 streamed `fixture-multi/cnctw` and observed chunk paths in sorted root
+  archive order: `cnctw/.local.installing/order/first.txt`, then
+  `cnctw/.local.installing/order/second.txt`.
+
 ### 2026-06-07 - Streamed Install Whole-Stream Retry (S42)
 
 - Code under test added S42 in `run_extended_scenarios.py`.