fix(codec): bound HELLO locator count by remaining bytes

[evshary]

Description

This PR makes HELLO locator decoding reject impossible locator counts before allocating memory. It turns malformed locator lists into normal deserialization failures instead of very large allocation attempts.

What does this PR do?

• Checks that the decoded locator count does not exceed the number of bytes remaining in the input buffer.
• Rejects malformed HELLO locator lists before allocating the locator array.

Why is this change needed?

Before this change, a malformed HELLO message could decode a huge locator count and try to allocate an extremely large locator array. This PR adds a simple bounds check based on the remaining input bytes so invalid messages fail cleanly and safely.

Related Issues

eclipse-zenoh/zenoh#2592

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Labels: bug

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