[TLS-02] Add rotating session-ticket key rings

Objective

Encrypt new tickets with the active key, decrypt with active and bounded previous keys, rotate without restart, zero retired key material, and cover cross-rotation resumption.

Deliverables

• Implement the complete scoped behavior without Git submodules.
• Keep public APIs explicit about ownership, resource limits, and errors.
• Add focused unit, integration, compatibility, fuzz, and benchmark coverage as applicable.
• Update documentation and machine-readable compatibility status.

Acceptance criteria

• The scoped implementation and tests are merged on main.
• Zig formatting, focused tests, and the repository CI suite pass.
• No unexplained compatibility skips, silent fallbacks, leaks, or unbounded hostile-input paths remain.
• Benchmarks or security evidence is attached when this affects a hot or untrusted path.

Relationships

• Parent: TLS-00

Blocked by

• TLS-01

Blocks

• TLS-04

Baselines

• Zig 0.17-dev resolved and locked through Pantry.
• ModSecurity 3.0.16, Coraza 3.7.0, CRS 4.28.0, and libinjection 4.0.0 where applicable.

Completed in 6071f79. New tickets use the active key; resumptions accept a synchronized bounded ring of one active plus three previous keys; duplicate names are rejected; retired key material is securely cleared; rotation requires no listener restart; and tests cover cross-rotation resumption plus bounded retirement. The issue was closed automatically on main.