Vec::drain with VecDeque::pop_front for O(1) log pruning across all apps

[AdityaShome]

Problem:

All three apps (mofa-fm, mofa-debate, mofa-asr) stored log entries in a Vec<String> capped at 5,000 entries. When full, Vec::drain(0..excess) removed the oldest shifting all remaining elements left in O(n) time. During active voice chat (logs arriving every 50ms), this caused periodic CPU spikes on the UI thread.

Additionally, mofa-debate had no pruning at all, allowing unbounded memory growth during long sessions.
Fixes: #40

Solution:

Switched from Vec<String> to VecDeque<String> with push_back() / pop_front() — O(1) per eviction. Same ring-buffer pattern already used in mofa-metrics/src/store.rs.

Changes:

File	Change
mod.rs (mofa-fm)	Vec<String> → VecDeque<String>
log_panel.rs (mofa-fm)	push → push_back, drain → pop_front + unit tests
audio_controls.rs (mofa-fm)	vec![...] → VecDeque::from(vec![...])
mod.rs (mofa-debate)	Vec<String> → VecDeque<String>
log_panel.rs (mofa-debate)	Same + added missing MAX_LOG_ENTRIES cap
audio_controls.rs (mofa-debate)	vec![...] → VecDeque::from(vec![...])
mod.rs (mofa-asr)	Vec<String> → VecDeque<String>
log_panel.rs (mofa-asr)	push → push_back, drain → pop_front

Benchmark: (200K inserts, release mode)

Approach	Time
Vec + drain(0..excess)	322ms
VecDeque + pop_front()	7.4ms
Speedup	44x

Testing:

• cargo check --workspace passes, no new warnings
• cargo test -p mofa-fm -- log_panel::tests 6/6 pass
• Tests cover: capacity limits, FIFO ordering, boundary conditions, batch inserts, clear

[Sourya07]

@AdityaShome issue #23
please take a look

[AdityaShome]

Hello, my PR #42 is different from #23 as #23 is about DirtyVec::push in mofa-dora-bridge/src/shared_state.rs.
My changes are in the app display layer: apps/mofa-fm/, apps/mofa-debate/, and apps/mofa-asr/, same class of O(n) bug with no overlap.
I also added a missing MAX_LOG_ENTRIES cap in mofa-debate that didn't exist anywhere and fixes how each app's log panel prunes its own display buffer. These two issues are independent and both need to be fixed.