chore: archive v1.0 MVP milestone

Archive roadmap and requirements to milestones/, reorganize ROADMAP.md,
evolve PROJECT.md with shipped state, create retrospective.

4 phases, 11 plans, 16/16 requirements — all complete.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/MILESTONES.md

@@ -0,0 +1,16 @@
+# Milestones
+
+## v1.0 MVP (Shipped: 2026-03-26)
+
+**Phases completed:** 4 phases, 11 plans, 9 tasks
+
+**Key accomplishments:**
+
+- Config-driven packet classifier with 12 protocol rules (ICMP, DNS, HTTPS, SSH, etc.) and 4 hash-bucketed unknown classes
+- Live packet capture via go-pcap with privilege detection, non-blocking channel pipeline, and atomic drop counter
+- Additive synthesis engine: per-class sine oscillators, EMA amplitude smoothing, constant-power stereo panning
+- MP3 encoding via embedded LAME (go-lame v0.0.9), zero-packet guard, `-o` flag with timestamp default
+- End-to-end pipeline: capture -> classify -> aggregate -> synthesize -> MP3 with clean Ctrl+C shutdown
+- BPF filter support (`--filter`) and offline pcap file sonification (`--read`) with timestamp-based windowing
+
+---