Unify app -> agent naming in handshake metadata (#190)

[octoaide]

Summary

This PR renames client handshake metadata fields that used
'app_' to 'agent_' to make it explicit that the client-side
component is an agent (not a standalone server). It aligns
ConnectionBuilder and AgentInfo naming, updates tests and the
CHANGELOG, and preserves wire compatibility.

What changed

• ConnectionBuilder: app_name -> agent_name, app_version ->
  agent_version (remote_* fields unchanged)
• AgentInfo: app_name/version -> agent_name/agent_version
• Tests: APP_NAME/APP_VERSION -> AGENT_NAME/AGENT_VERSION
• Added serde compatibility: deserialization accepts legacy
  keys (app_name, app_version, version) so existing handshake
  payloads continue to be accepted
• CHANGELOG and Cargo.toml updated; unit tests added/updated

Compatibility notes

• Bincode handshake payloads remain compatible (field order
  and types unchanged)
• JSON/serde deserialization is backward compatible with the
  legacy key names listed above

Files touched (high level)

• src/client.rs
• src/lib.rs
• src/test.rs
• Cargo.toml
• CHANGELOG.md

References

Closes #190
#190

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.61%. Comparing base (257921f) to head (e5cc047).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #199   +/-   ##
=======================================
  Coverage   85.61%   85.61%           
=======================================
  Files          15       15           
  Lines        6481     6481           
=======================================
  Hits         5549     5549           
  Misses        932      932           

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[pott-cho]

Could you make the following changes?

1. Remove the tests added in lib.rs. I think they are unnecessary for this change.

2. Update the app-like test value in client.rs.
   There is still an app-like test value:

   ConnectionBuilder::new(
       "test-server",
       "127.0.0.1:443".parse().unwrap(),
       "app",
       ...
   )

   Since this PR renames the client-side metadata to agent_*, please update this value to something agent-oriented, such as "test-agent", for consistency.

3. Revise the CHANGELOG entry.
   The current CHANGELOG entry seems a bit misleading. Please change it to something like this:

   - Renamed handshake metadata fields from `app_name` / `version` to
     `agent_name` / `agent_version` in `ConnectionBuilder` and `AgentInfo`.
   

4. Fix the CHANGELOG format.

   Please change ## Unreleased to ## [Unreleased], and add the [Unreleased] link reference at the bottom of the file. For example:

   [Unreleased]: https://github.com/petabi/review-protocol/compare/0.19.0...main
   

[octoaide]

I reviewed your comments and made the requested changes — then committed and pushed them.

What I changed

• Removed the unit tests in lib.rs: I deleted the four agent_info_* serialization/deserialization tests and the sample_agent_info helper (these were redundant for this change).
• Updated client.rs tests: replaced the app-like test value ("app") with an agent-oriented value ("test-agent") in the four ConnectionBuilder::new calls used by the certificate-chain tests.
• Updated CHANGELOG: rewrote the Unreleased line to clearly state the intent:
  • "Renamed handshake metadata fields from app_name / version to agent_name / agent_version in ConnectionBuilder and AgentInfo."
  • Fixed the header to ## [Unreleased] and added the link reference at the bottom:
    [Unreleased]: 0.19.0...main
• Cleanups: removed now-unused imports (std::net) from the lib.rs test module after removing those tests.

Verification

• Ran cargo test --all-features — all tests passed (200 tests) with no warnings.

Thanks for the clear review — these updates should address all four items you raised. If you want the CHANGELOG wording adjusted further, I can tweak it.

[pott-cho]

serde_json is no longer used anywhere. Please remove it.

[octoaide]

I reviewed your comment and found that serde_json was no longer referenced anywhere in the codebase. I removed the unused dependency (serde_json = "1.0.150") from Cargo.toml, committed the change, and pushed it to the branch.

This keeps the manifest lean and avoids shipping an unnecessary dependency. I also verified the project builds after the removal. Thanks for pointing that out — it’s been addressed.

[pott-cho]

Please remove the serde attributes above.