fix: wasm_memory_threshold is now bounded by 256TiB (#304)

This PR updates the maximum allowed value for wasm_memory_threshold to
match that of wasm_memory_limit which also restricts (with a different
semantics) wasm memory usage and thus using the same maximum allowed
value makes sense. Both values are now specified to be up to `2^{48}`
bytes (256 TiB), reflecting the replica
[PR](dfinity/ic#10574) for
`wasm_memory_threshold` and the actual maximum allowed value for
`wasm_memory_limit` already in place (`2^{48}` bytes rather than
`2^{48}-1` bytes).

Author: mraszyk

docs/references/ic-interface-spec/changelog.md

@@ -15,6 +15,7 @@ sidebar:
   delegations are not accepted; the value `"all"` permits all kinds of requests, same as
   omitting the field. Requests of any kind carrying a delegation with any other value of
   the `permissions` field are not accepted.
+* `wasm_memory_threshold` in canister settings is now bounded by 2<sup>48</sup>, analogously to `wasm_memory_limit`.
 
 ### 0.63.0 (2026-06-29) {$0_63_0}
 * Support for the HTTP method `PATCH` in canister `http_request` in non-replicated mode.

docs/references/ic-interface-spec/management-canister.md

@@ -79,7 +79,7 @@ The optional `settings` parameter can be used to set the following settings:
 
 -   `wasm_memory_limit` (`nat`)
 
-    Must be a number between 0 and 2<sup>48</sup>-1 (i.e., 256TB), inclusively, and indicates the upper limit on the WASM heap memory consumption of the canister in bytes.
+    Must be a number between 0 and 2<sup>48</sup>, inclusively, and indicates the upper limit on the WASM heap memory consumption of the canister in bytes.
 
     An operation (update method, canister init, canister post_upgrade) that causes the WASM heap memory consumption to exceed this limit will trap.
     The WASM heap memory limit is ignored for query methods, response callback handlers, global timers, heartbeats, and canister pre_upgrade.
@@ -115,7 +115,7 @@ The optional `settings` parameter can be used to set the following settings:
 
 -   `wasm_memory_threshold` (`nat`)
 
-    Must be a number between 0 and 2<sup>64</sup>-1, inclusively, and indicates the threshold on the remaining wasm memory size of the canister in bytes:
+    Must be a number between 0 and 2<sup>48</sup>, inclusively, and indicates the threshold on the remaining wasm memory size of the canister in bytes:
     if the remaining wasm memory size of the canister is below the threshold, execution of the ["on low wasm memory" hook](./canister-interface.md#on-low-wasm-memory) is scheduled.
 
     Default value: 0 (i.e., the "on low wasm memory" hook is never scheduled).