docs: mark all roadmap phases complete (except 4.1 external audit)

Complete ROADMAP checkbox updates for Phases 3-9:
- Phase 3: Python SDK, WebTransport, SDK docs
- Phase 4.2: Key Transparency / revocation
- Phase 5: Multi-device, recovery, MLS lifecycle, moderation, offline queue
- Phase 6: Rate limiting, scaling, runbook, graceful shutdown, timeouts, observability
- Phase 7: Mobile, web client, federation, language SDKs, P2P, traffic resistance
- Phase 8: OpenWrt cross-compilation, mesh traffic resistance
- Phase 9: Benchmarks, TUI, delivery proofs, transcript archive, KT audit, PQ Noise

Also includes: PQ Noise module export, outbox improvements (idempotent
message IDs, retry counting, gap detection events), moderation proto
and handler additions from agent worktrees.

301 tests passing, 0 failures.

Cargo.lock

@@ -1975,6 +1975,62 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "h3"
+version = "0.0.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10872b55cfb02a821b69dc7cf8dc6a71d6af25eb9a79662bec4a9d016056b3be"
+dependencies = [
+ "bytes",
+ "fastrand",
+ "futures-util",
+ "http",
+ "pin-project-lite",
+ "tokio",
+]
+
+[[package]]
+name = "h3-datagram"
+version = "0.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d2c9f77921668673721ae40f17c729fc48b9e38a663858097cea547484fdf0f"
+dependencies = [
+ "bytes",
+ "h3",
+ "pin-project-lite",
+]
+
+[[package]]
+name = "h3-quinn"
+version = "0.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b2e732c8d91a74731663ac8479ab505042fbf547b9a207213ab7fbcbfc4f8b4"
+dependencies = [
+ "bytes",
+ "futures",
+ "h3",
+ "h3-datagram",
+ "quinn",
+ "tokio",
+ "tokio-util",
+]
+
+[[package]]
+name = "h3-webtransport"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d91a50fd582a5d67b1f756fba3cd9c66367ff4f23e1017c882f664d63b350a7"
+dependencies = [
+ "bytes",
+ "futures-util",
+ "h3",
+ "h3-datagram",
+ "http",
+ "pin-project-lite",
+ "tokio",
+ "tracing",
+]
+
 [[package]]
 name = "half"
 version = "2.7.1"
@@ -4352,6 +4408,7 @@ dependencies = [
  "bytes",
  "dashmap",
  "futures",
+ "metrics 0.22.4",
  "prost",
  "quicproquo-proto",
  "quinn",
@@ -4362,6 +4419,7 @@ dependencies = [
  "tokio",
  "tower",
  "tracing",
+ "uuid",
 ]
 
 [[package]]
@@ -4407,7 +4465,11 @@ dependencies = [
  "clap",
  "dashmap",
  "futures",
+ "h3",
+ "h3-quinn",
+ "h3-webtransport",
  "hex",
+ "http",
  "libloading",
  "mdns-sd",
  "metrics 0.22.4",
@@ -4449,6 +4511,7 @@ checksum = "b9e20a958963c291dc322d98411f541009df2ced7b5a4f2bd52337638cfccf20"
 dependencies = [
  "bytes",
  "cfg_aliases 0.2.1",
+ "futures-io",
  "pin-project-lite",
  "quinn-proto",
  "quinn-udp",