fix(protocol): drop all removable timers in construct_set_timers

[bluetoothbot]

What

Fix construct_set_timers dropping only some inactive/expired timers because it mutated the list while iterating it.

Why

The cleanup loop called timer_list.remove(t) during for t in timer_list. Each removal shifts later elements left, so the iterator skips the element right after a removed one. Adjacent removable timers — or an active-but-expired timer following any removed timer — survived into the outgoing 0x21 message, sending stale timers to the device.

How

Set length on every timer first, then filter the list in place with a comprehension (timer_list[:] = [...]). Keeps the existing in-place mutation contract callers rely on, and preserves the later truncate/pad logic.

Testing

• New test_construct_set_timers_drops_all_removable_timers: two adjacent active-but-expired timers must serialize identically to an empty list (six inactive padding slots). Fails on the old code, passes now.
• Full suite: 141 passed, ruff clean.

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Quality Report

Changes: 2 files changed, 27 insertions(+), 2 deletions(-)

Code scan: clean

Tests: failed (FAILED)

Branch hygiene: clean

Generated by Kōan

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
flux_led/protocol.py	99.13% <100.00%> (-0.01%)	⬇️

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