Real-time scheduling

Foundation capability (taktora-executor v0.1): worker threads can be pinned and prioritized for predictable latency on PREEMPT_RT-capable Linux systems.

Feature: Real-time worker scheduling FEAT_0015
status: open
satisfies: FEAT_0010
is satisfied by: REQ_0040, REQ_0041
is implemented by: BB_0029

Worker threads can be pinned and prioritized for predictable latency on PREEMPT_RT-capable Linux systems.
Requirement: Core-affinity assignment REQ_0040
status: implemented
satisfies: FEAT_0015
is verified by: TEST_0127
links outgoing: BB_0029, TEST_0127

The runtime shall, behind the thread_attrs feature, allow worker threads to be pinned to a specified set of CPU cores.
Requirement: SCHED_FIFO priority on Linux REQ_0041
status: implemented
satisfies: FEAT_0015
is verified by: TEST_0128
links outgoing: BB_0029, TEST_0128

The runtime shall, behind the thread_attrs feature on Linux, allow worker threads to run under SCHED_FIFO at a configured priority, subject to the process holding CAP_SYS_NICE.