feat(ffi): expose Room.get_state_event(), Room.account_data(), and Room.set_account_data()

[lucasfeijo]

Expose room-scoped state event reading and account data read/write through the FFI bindings.

Motivation

Non-Rust clients (Swift/iOS, Kotlin/Android) currently have no way to read arbitrary room state events or room-scoped account data through FFI. The underlying SDK already has Room::get_state_event(), Room::account_data(), and Room::set_account_data_raw() — this PR surfaces them.

• Room.account_data(event_type) / Room.set_account_data(event_type, content) follow the same pattern as the existing Client.account_data() / Client.set_account_data()
• Room.get_state_event(event_type, state_key) complements the already-merged Room.send_state_event_raw() (feat(ffi): expose Room.send_state_event_raw() #6350) with the read side

Tested by integrating a build into our iOS application.

• I've documented the public API Changes in the appropriate CHANGELOG.md files.
• This PR was made with the help of AI.

Signed-off-by:

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.83%. Comparing base (ba46159) to head (4e78fa7).
⚠️ Report is 33 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6430      +/-   ##
==========================================
+ Coverage   89.82%   89.83%   +0.01%     
==========================================
  Files         378      378              
  Lines      103931   103931              
  Branches   103931   103931              
==========================================
+ Hits        93351    93367      +16     
+ Misses       6995     6982      -13     
+ Partials     3585     3582       -3     

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[codspeed-hq]

Merging this PR will degrade performance by 49.63%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 49 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	Restore session [memory store]	112 ms	222.2 ms	-49.63%

---

_{Comparing lucasfeijo:feat/ffi-room-state-and-account-data (4e78fa7) with main (3d29db5)}

[lucasfeijo]

This looks like a false positive, because the changes don't touch any code paths related to session restore or memory store, the PR only adds account_data(), set_account_data(), and get_state_event() as new methods on Room. No existing code is modified.

[bnjbvr]

It's indeed a false positive, this benchmark unfortunately is bimodal.

[bnjbvr]

Thanks, makes sense! Small suggestions below

[bnjbvr]

Can you apply the renamings here too, add the point about custom events, and include the PR number as done on other lines below?