feat(ktrace): added derived CPU slices, thread states, threads and processes to ktrace-decode

[FlareCoding]

Summary

• Questions about scheduling and per-process time made every analysis rebuild CPU timelines and thread states from raw switches and wakeups, which is easy to get subtly wrong.
• ktrace-decode derives them once: cpu_slices, thread_states (running, runnable or sleeping, with the waker, switch reason or syscall behind each stretch), threads, thread_names and processes. Anything the records cannot determine is left out or NULL rather than guessed, and a switch_chain health check confirms the chain of switches these tables rely on is unbroken.
• Thread and time indexes on the event and derived tables keep per-thread queries fast.

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Note

Medium Risk
Large new timeline interpretation logic drives correctness of derived scheduling data; mistakes would mislead offline analysis but do not affect runtime kernel behavior.

Overview
ktrace-decode now materializes scheduling-oriented SQLite tables so analyses do not have to rebuild CPU timelines and thread lifetimes from raw sched_switch / sched_wakeup events. A new write_derived_tables pass walks the ordered timeline and populates cpu_slices, thread_states (running / runnable / sleeping, with waker, switch reason, and syscall or page-fault context when the trace supports it), threads, thread_names, and processes, using NULL where the records do not prove a value.

Pipeline and schema wiring changes: task-name interning moves into shared name_table (name_ids flows through event and derived writers); event table creation drops the inline names schema and instead auto-creates (tid, ts_ns) indexes on event fields whose names end in tid. Health checks gain a switch_chain validation that each CPU’s switches continue from the previous task, and check_health now takes the full timeline. CLI output reports derived row counts; record_event_id / record_payload helpers centralize record parsing.

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