Make the edge protocol contract test pass on its own

tests/edge_protocol.test.ts validates schemas carrying format: "uuid" and
format: "uri" but registered neither. TypeBox treats an unregistered
format as a failure, not a pass, so every start_print in that file was
rejected - and the file still went green, because some other test in the
same run imported Elysia first and registered the formats globally. Run
alone it failed. A contract test that depends on which files ran before
it is the worst way for one to behave.

It now imports src/validation/formats, which exists for exactly this and
gains a "uri" validator: anything the platform parses as an absolute URL.
Lenient on purpose - the only user is a presigned object-store GET that
this backend mints itself, so a stricter pattern would have to anticipate
whatever query parameters a signer adds, and rejecting a URL R2 would
have honoured costs a print for no security.

src/validation/formats.ts

@@ -3,6 +3,12 @@ import { FormatRegistry } from "@sinclair/typebox";
 /**
  * Registers the string formats this codebase uses with TypeBox.
  *
+ * Import this from any test that validates a schema carrying a `format`
+ * without standing up Elysia. `tests/edge_protocol.test.ts` did not, and so
+ * passed only because some *other* test file in the same run happened to
+ * import Elysia first and register the formats globally - run on its own it
+ * failed, which is the worst way for a contract test to behave.
+ *
  * TypeBox ships no format validators: `format` is a registry lookup, and an
  * *unregistered* format does not pass - it fails. So a schema written with
  * `format: "uuid"` and checked outside Elysia rejects every value, including
@@ -28,6 +34,24 @@ if (!FormatRegistry.Has("uuid")) {
   FormatRegistry.Set("uuid", (value) => UUID.test(value));
 }
 
+if (!FormatRegistry.Has("uri")) {
+  // `PrinterCommand.start_print.url` is the only user, and it carries a
+  // presigned object-store GET. Lenient on purpose: anything the platform
+  // parses as an absolute URL passes. A stricter pattern would have to
+  // anticipate whatever query parameters a signer adds, and rejecting a URL
+  // R2 would have honoured costs a print for no security - the command is
+  // minted by this backend, not submitted by a client.
+  FormatRegistry.Set("uri", (value) => {
+    try {
+      // Rejects a relative reference, which `format: "uri"` is supposed to:
+      // the two-argument form would happily resolve "../x" against a base.
+      return new URL(value).protocol.length > 0;
+    } catch {
+      return false;
+    }
+  });
+}
+
 if (!FormatRegistry.Has("date-time")) {
   // Deliberately lenient: anything `Date.parse` understands. The producers
   // are `new Date().toISOString()` in TypeScript and chrono's RFC 3339 in