refactor(cuprate): one CUPRATE_MIN_DISK_GB, manifest matches it (review)

450 existed as two independent Rust constants (RPC gates vs boot
reconciler) linked only by a "keep in lockstep" comment — updating one
would reopen the disk-fill hole. Move it to crate::constants as the
single source of truth both paths import.

Also raise apps/cuprate/manifest.yml storage dependency and disk_limit
from 300Gi to 450Gi so manifest-driven surfaces (store size, pre-checks)
show the number the gate actually enforces — a user provisioning to the
displayed 300 was refused at an unexplained 450. Catalog regenerated
(cuprate entry re-embedded; still unsigned pending sign-catalog.sh).

core/archipelago/src/constants.rs

@@ -9,3 +9,19 @@ pub const DWN_HEALTH_URL: &str = "http://127.0.0.1:3100/health";
 
 /// Tor SOCKS5 proxy for outbound onion connections.
 pub const TOR_SOCKS_PROXY: &str = "socks5h://127.0.0.1:9050";
+
+/// Smallest disk (GB, total) a cuprate node may be installed, started,
+/// restarted, updated, or boot-reconciled onto. Cuprate has no on-disk
+/// pruning (verified against upstream `cuprated/src/config.rs` — the
+/// `pruning` crate is Monero's p2p protocol pruning), so unlike the bitcoin
+/// apps it cannot self-shrink on a scarce disk; below this line the ~250 GiB
+/// Monero chain simply does not fit and running it would fill the filesystem
+/// and take Archipelago down. 450 = chain + growth/headroom: allows
+/// 500 GB-class disks, refuses the 250 GB VPS class.
+///
+/// SINGLE SOURCE OF TRUTH — the RPC gates
+/// (`api::rpc::package::dependencies`) and the boot reconciler
+/// (`container::prod_orchestrator`) both read this; a drift between them
+/// would silently reopen the disk-fill failure the gate exists to close.
+/// Keep `apps/cuprate/manifest.yml` (storage dependency + comments) aligned.
+pub const CUPRATE_MIN_DISK_GB: u64 = 450;