fix: map 404 responses to NotFoundError in REST and Bridge transports

[1HazyOne707]

Problem

getEntity() throws TransportError instead of NotFoundError when an entity does not exist. This breaks typed catch blocks:

try {
  await memory.longTerm.getEntity("ent-00000000-0000-0000-0000-000000000000");
} catch (e) {
  console.log(e instanceof NotFoundError);  // false — wrong
  console.log(e instanceof TransportError); // true  — wrong
}

Root cause

Both RestTransport and BridgeTransport map all non-OK HTTP responses to TransportError, including 404s.

Fix

Add a response.status === 404 check before the generic error path in both transports and throw NotFoundError with the same message. Added NotFoundError import to both files.

Closes #125

[vercel]

@1HazyOne707 is attempting to deploy a commit to the lyonwj's projects Team on Vercel.

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[1HazyOne707]

Hey @lyonwj — could you authorize the Vercel preview when you get a chance? Thanks!

[1HazyOne707]

Hey @lyonwj — just checking in on #147, #148, and #149 whenever you get a chance. Happy to make any adjustments needed. Thanks!