perf(profiler): reserve(1+|pids|) for errs slice — eliminate O(log n) reallocations in Flush

[KorsarOfficial]

Closes #92

Complexity analysis

Let k = len(c.p.pids) (number of tracked PIDs).

	Before	After
Initial capacity	0	1 + k
append reallocations	⌈log₂(1 + k)⌉	0
Heap allocations	1 + ⌈log₂(1+k)⌉	1

The standard Go append doubling strategy means make([]error, 0) triggers reallocations at sizes 1, 2, 4, 8 … up to 1+k. With a correct capacity hint the backing array is allocated once at the final size.

Change

// Before — O(log k) reallocations
errs := make([]error, 0)

// After — O(1) single allocation, capacity = worst-case append count
errs := make([]error, 0, 1+len(c.p.pids))

The bound 1 + len(c.p.pids) is tight: at most one error from wholeSystem flush + one per PID consumer.

[KorsarOfficial]

📄 Full analysis report (PDF): 08-perforator-optimizations.pdf

Covers complexity analysis, concurrency audit, and verification for all 7 optimizations.