Release v0.3.0: native TCP safety

[puffball1567]

Changes

• Negotiate wire version on every new connection; bound frames, deadlines and redirects.
• Add typed errors while retaining KoutenError compatibility.
• Remove unsafe automatic write replay and all-peer miss probing.
• Preserve empty values and complete IDs in ordered batch_get via GETID requests; this increases request count compared with legacy BGET.
• Make close terminal and serialize client operations.
• Prepare v0.3.0 with a behavior-change guide.

Validation

• Shared 27-case protocol/failure matrix and six authentication/TLS configurations passed.
• All 17 unit, two-node integration and crypto tests passed.
• Wheel/source distribution builds passed.
• Add Linux/macOS conformance CI.