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-db/src/db.rs

@@ -252,46 +252,11 @@ impl GameCatalog {
     }
 }
 
-#[derive(Clone, Serialize, Deserialize)]
-pub struct GameFileDescription {
-    pub game_id: String,
-    pub relative_path: String,
-    pub is_dir: bool,
-    pub size: u64,
-}
-
-impl GameFileDescription {
-    #[must_use]
-    pub fn is_version_ini(&self) -> bool {
-        let expected = format!("{}/version.ini", self.game_id);
-        self.relative_path.replace('\\', "/") == expected
-    }
-
-    #[must_use]
-    pub fn file_size(&self) -> u64 {
-        if self.is_dir { 0 } else { self.size }
-    }
-}
-
-impl fmt::Debug for GameFileDescription {
-    #[allow(clippy::cast_precision_loss)]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "{}: [{}] path:{} size:{}",
-            self.game_id,
-            if self.is_dir { 'D' } else { 'F' },
-            self.relative_path,
-            self.size,
-        )
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use serde_json::json;
 
-    use super::{Availability, Game, GameFileDescription};
+    use super::{Availability, Game};
 
     fn game_fixture() -> Game {
         Game {
@@ -364,42 +329,4 @@ mod tests {
         game.downloaded = true;
         assert_eq!(game.normalized_availability(), Availability::Ready);
     }
-
-    #[test]
-    fn version_ini_predicate_matches_only_game_root_sentinel() {
-        let root = GameFileDescription {
-            game_id: "aoe2".to_string(),
-            relative_path: "aoe2/version.ini".to_string(),
-            is_dir: false,
-            size: 8,
-        };
-        assert!(root.is_version_ini());
-
-        let nested = GameFileDescription {
-            game_id: "aoe2".to_string(),
-            relative_path: "aoe2/local/version.ini".to_string(),
-            is_dir: false,
-            size: 8,
-        };
-        assert!(!nested.is_version_ini());
-
-        let other_game = GameFileDescription {
-            game_id: "aoe2".to_string(),
-            relative_path: "other/version.ini".to_string(),
-            is_dir: false,
-            size: 8,
-        };
-        assert!(!other_game.is_version_ini());
-    }
-
-    #[test]
-    fn version_ini_predicate_accepts_windows_separators() {
-        let root = GameFileDescription {
-            game_id: "aoe2".to_string(),
-            relative_path: r"aoe2\version.ini".to_string(),
-            is_dir: false,
-            size: 8,
-        };
-        assert!(root.is_version_ini());
-    }
 }