feat: add configurable Call-ID generators

[darwvin-dev]

Summary:
Add a new -cid_type option for built-in Call-ID generators while keeping -cid_str as the default behavior. This adds UUID, compact UUID, random, and timestamp-based Call-ID modes, along with unit coverage for each mode.

Reasoning:
-cid_str is flexible and should remain the default, but it still assumes callers want to describe the Call-ID shape as a formatting pattern. In practice there are cases where a ready-made generator is more convenient or more consistent: interoperability testing against systems that expect UUID-like identifiers, quickly switching between predictable and opaque identifiers during troubleshooting, and avoiding repeated hand-built templates for common styles.

This change keeps backward compatibility by leaving -cid_str and the legacy formatting path untouched unless -cid_type is explicitly selected. The new modes provide a small set of built-in generators that cover the common cases without removing the existing customization path.

• New -cid_type CLI option.
• Built-in default, uuid, uuid-compact, random, and timestamp generator modes.
• Existing -cid_str behavior retained as the default path.
• Unit coverage for each mode.

[darwvin-dev]

Follow-up on the GitHub Advanced Security note: the latest commit (ec7ff64) removes the custom loop-counter option parser path and reuses the existing string option parsing path, then validates -cid_type after option parsing.

The current GitHub Actions runs show action_required rather than executing jobs, so I cannot get a fresh hosted CI result until a maintainer approves the workflows for this PR.

[Copilot]

Pull request overview

This PR adds a new -cid_type CLI option to select built-in Call-ID generator modes (while preserving -cid_str as the default/legacy formatting path), and introduces unit tests validating the generated Call-ID shapes.

Changes:

• Added -cid_type option parsing with supported Call-ID modes (default/format, uuid, uuid-compact, random, timestamp).
• Refactored Call-ID construction into dedicated helper functions and added new generator implementations.
• Added unit tests covering each Call-ID generation mode.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/sipp.cpp	Adds -cid_type option, parses/validates the selected Call-ID mode.
src/call.cpp	Implements the new Call-ID generators, routes call creation through the selected mode, and adds unit tests.
include/sipp.hpp	Introduces CID_MODE_* constants and a global call_id_mode setting.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[orgads]

Since you already refactor, please C++-ify it. Make it a class, and use std::ostringstream instead of a bunch of static functions.

[darwvin-dev]

Thanks for the review done in 221dbb9: Call-ID generation is now handled by a CallIdBuilder class using std::ostringstream btw fixed the trailing % edge case and updated the -cid_type help text to match the accepted aliases.

[orgads]

Thank you!