fix(q): validate table wire markers

[belowzeroff]

Summary

• validate the table dictionary marker during q deserialization
• propagate deserialization errors before trailing-byte checks
• add a regression test for malformed table markers

Testing

• codec self-test coverage added in test/driver.c

[protocolstardust]

Superseded by #10: its first commit is this exact change (810a23e), so it landed on master with #10 (e08ab96) and GitHub has marked this PR merged. Review notes are on #10.