feat(peer)!: cut over to authenticated catalog sharing

Replace address-only trust and pushed peer state with installation identities,
SPKI-pinned QUIC, candidate-only discovery, and bounded responder-owned
protocol-8 pulls. The runtime now owns each network generation and all admitted
work through shutdown.

Add exact bundled content identities, reproducible manifest publishing,
capability-confined downloads, streaming BLAKE3 verification, quarantine and
retry, and crash-recoverable download and install transactions. Ship generated
fixture catalogs and fail closed when production manifests are absent.

The Tauri backend exposes durable sharing policy, redacted identity state, and
attempt-keyed transfer snapshots. Frontend consumption follows in the next
commit. Repository-wide test certificates and protocol-7 paths are removed.

BREAKING CHANGE: peers must use protocol 8 and exact catalog content artifacts;
protocol-7 frames and shared-certificate identities are no longer accepted.

Test Plan:
- `just test` -- passed on the completed stack (708 workspace tests)
- `just clippy` -- passed on the completed stack
- `just build` -- passed with fixture catalogs on the completed stack
- `just catalog-check-production` -- failed closed because the external
  production manifest corpus is absent
- `git diff --cached --check` -- passed

crates/lanspread-peer-cli/catalogs/unknown/manifests/catalog-content-index-v1.jsonl

@@ -0,0 +1 @@
+{"schema_version":1,"games":{"cod2":{"game_version":"20160922","content_id":"6f60950ccdb7ec12e8e9b68210bb345994490dd5ca761c063ac27a6caf250071","supports_streamed_install":false}}}

crates/lanspread-peer-cli/catalogs/unknown/manifests/cod2.json

@@ -0,0 +1,28 @@
+{
+  "schema_version": 1,
+  "game_id": "cod2",
+  "game_version": "20160922",
+  "chunk_size": 134217728,
+  "files": [
+    {
+      "canonical_path": "catalog-unknown.txt",
+      "kind": "file",
+      "size": 73,
+      "file_blake3": "11bd8035dcf904c547896565bbc8b9ae47b1044ac21ebf732a51820caddfc819",
+      "chunk_blake3": [
+        "11bd8035dcf904c547896565bbc8b9ae47b1044ac21ebf732a51820caddfc819"
+      ]
+    },
+    {
+      "canonical_path": "version.ini",
+      "kind": "file",
+      "size": 9,
+      "file_blake3": "91c51abb1c7e7a6426bc9003603608587648bd1fed32b0cf3e81bc5ad76531b4",
+      "chunk_blake3": [
+        "91c51abb1c7e7a6426bc9003603608587648bd1fed32b0cf3e81bc5ad76531b4"
+      ]
+    }
+  ],
+  "streamed_install_files": [],
+  "content_id": "6f60950ccdb7ec12e8e9b68210bb345994490dd5ca761c063ac27a6caf250071"
+}