Merge maint into master after v0.2.1 release

Uses the 'ours' merge strategy to keep all of master's tree
verbatim with one carve-out: the v0.2.1 release notes archive at
docs/releases/release-notes-v0.2.1.md is retained as a permanent
docs artifact.

Discarded from maint's release-prep commit: Cargo.toml / Cargo.lock
version bumps (master stays on v0.3.0-dev), README v0.2.1 badge and
prose, and the RELEASE-NOTES.md root mirror (master's root mirror
will eventually carry the v0.3.0 release notes when v0.3.0 ships
from this line).

CHANGELOG: the v0.2.1 release section is integrated between
[Unreleased] (v0.3.0-dev work) and the [0.2.0] historical section.
Items that landed on maint during the v0.2.1 cycle are removed
from [Unreleased] so [0.2.1] is the canonical home for those
changes (Linux release artifact and AUR workflows; bloom fill-ratio
validation; seven maint-line bug fixes).

docs/releases/release-notes-v0.2.1.md

@@ -0,0 +1,141 @@
+# FIPS v0.2.1
+
+**Released**: 2026-05-11
+
+v0.2.1 is a maintenance release on the v0.2.x line. No new features
+and no wire-format changes; operators running v0.2.0 can upgrade in
+place. The release rolls up bug fixes and operational hardening for
+issues surfaced in v0.2.0 deployments, plus a bloom-filter fill-ratio
+validation that protects mesh-size estimates from saturated-filter
+inputs.
+
+## At a glance
+
+- 22 commits since v0.2.0, 5 committers plus 2 issue reporters.
+- All changes are backwards-compatible with v0.2.0 on the wire.
+- Bloom filter fill-ratio validation hardens the FilterAnnounce
+  ingress path.
+- TreeAnnounce ancestry validation tightened to match the
+  spanning-tree specification.
+- Signed-tarball + `.deb` artifact workflow added for tagged
+  releases; AUR auto-publish on stable tags.
+
+## Behavior changes worth flagging
+
+- **Bloom filter fill-ratio validation** runs on every inbound
+  `FilterAnnounce`. Filters whose derived false-positive rate exceeds
+  `node.bloom.max_inbound_fpr` (new config field, default `0.05`) are
+  rejected silently on the wire, logged at WARN, and counted in a
+  new `bloom.fill_exceeded` counter. A rate-limited WARN also fires
+  when the local outgoing filter exceeds the cap.
+  `BloomFilter::estimated_count` now takes `max_fpr` and returns
+  `Option<f64>`, returning `None` for saturated filters; this
+  propagates through `compute_mesh_size` into `estimated_mesh_size`.
+- **TreeAnnounce ancestry validation** is now run before tree-state
+  mutation, enforcing ancestry-self-match, root-single-entry,
+  parent-second-entry, and root-is-minimum-NodeAddr. Non-conforming
+  announces are rejected with a WARN. Mixed v0.2.0 / v0.2.1 meshes
+  may produce WARN log lines on the v0.2.1 side until all peers
+  upgrade; behavior is correct, log noise only.
+
+## Notable bug fixes
+
+- **Control socket path detection** in `fipsctl` and `fipstop` now
+  checks for the `/run/fips/` directory instead of the socket file
+  inside it. Users not yet in the `fips` group get a clear
+  "Permission denied" error instead of a misleading "No such file"
+  fallback to `$XDG_RUNTIME_DIR`
+  ([#30](https://github.com/jmcorgan/fips/issues/30), reported by
+  [@Sebastix](https://github.com/Sebastix)).
+- **`fd00::/8` routing protected from Tailscale interception.** The
+  daemon installs an IPv6 routing-policy rule
+  (`ip -6 rule to fd00::/8 lookup main priority 5265`) at TUN setup,
+  so Tailscale's table 52 default route can no longer divert mesh
+  traffic.
+- **Bloom filter routing greedy-tree fallback.** `find_next_hop` no
+  longer returns `NoRoute` when the bloom candidate set is non-empty
+  but no candidate is strictly closer than the current node; it
+  falls through to greedy tree routing instead. Previously, this
+  caused dropped packets in topologies where the tree parent was
+  closer but not a bloom candidate.
+- **Auto-connect peers reconnect after a graceful Disconnect.**
+  Previously, a clean upstream shutdown left the auto-connect peer
+  orphaned; only the link-dead, decrypt-fail, and peer-restart paths
+  scheduled a reconnect
+  ([#60](https://github.com/jmcorgan/fips/issues/60), reported by
+  [@SwapMarket](https://github.com/SwapMarket)).
+- **`fipsctl connect` rejects FIPS mesh addresses** (`fd00::/8`) for
+  `udp`, `tcp`, and `ethernet` transports with a clear error message
+  instead of echoing success while the daemon silently failed the
+  bind with `EAFNOSUPPORT`
+  ([#61](https://github.com/jmcorgan/fips/issues/61), reported by
+  [@SwapMarket](https://github.com/SwapMarket)).
+- **OpenWrt ipk** cross-compiles cleanly again after excluding the
+  BLE feature that requires D-Bus, which is unavailable on OpenWrt
+  targets.
+
+## Packaging
+
+- **Linux release artifact workflow** builds x86_64 and aarch64
+  tarballs and `.deb` packages on `v*` tag push, with SHA-256
+  checksums, and publishes them to the GitHub release page.
+- **AUR publish workflow** auto-publishes the `fips` PKGBUILD on
+  stable `v*` tags.
+
+## Upgrade notes
+
+Operator-actionable items when moving from v0.2.0 to v0.2.1:
+
+- **Bloom filter fill-ratio cap (default 0.05).** Inbound
+  `FilterAnnounce` messages whose derived FPR exceeds the cap are
+  rejected silently on the wire. Operators with unusually saturated
+  filters in the field may want to confirm that the default applies
+  cleanly to their deployment; check the new `bloom.fill_exceeded`
+  counter if mesh-size estimates drift after upgrade.
+- **TreeAnnounce ancestry tightening.** Mixed v0.2.0 / v0.2.1 meshes
+  may produce WARN log lines on the v0.2.1 side until all peers
+  upgrade. Behavior is correct, log noise only.
+
+## Getting v0.2.1
+
+- **Linux x86_64 / aarch64**: `.deb` and tarball at the
+  [v0.2.1 release page](https://github.com/jmcorgan/fips/releases/tag/v0.2.1).
+- **Arch Linux**: `fips` from the AUR.
+- **OpenWrt**: `.ipk` at the v0.2.1 release page.
+- **From source**: `cargo build --release` from a checkout of the
+  v0.2.1 tag.
+
+The full per-commit changelog lives in
+[`CHANGELOG.md`](../../CHANGELOG.md). Issues and discussion at
+[github.com/jmcorgan/fips](https://github.com/jmcorgan/fips).
+
+## Contributors
+
+Thanks to everyone who contributed code or bug reports to this
+release.
+
+**Code and packaging**:
+
+- [@jcorgan](https://github.com/jmcorgan): release shepherd, bloom
+  fill-ratio validation, auto-connect reconnect fix, `fipsctl`
+  mesh-address rejection, control-socket path detection,
+  Tailscale-vs-`fd00::/8` routing policy, bloom routing greedy
+  fallback, rustfmt baseline.
+- [@Origami74](https://github.com/Origami74): OpenWrt ipk
+  BLE-feature build fix.
+- [@jodobear](https://github.com/jodobear): Linux release-artifact
+  workflow and target-aware build scripts.
+- [@dskvr](https://github.com/dskvr): AUR publish workflow.
+- [@SatsAndSports](https://github.com/SatsAndSports): TreeAnnounce
+  semantic validation.
+
+**Issue reports that drove fixes in this release**:
+
+- [@Sebastix](https://github.com/Sebastix): `fipsctl` / `fipstop`
+  control-socket path detection
+  ([#30](https://github.com/jmcorgan/fips/issues/30)).
+- [@SwapMarket](https://github.com/SwapMarket): auto-connect
+  reconnect after graceful disconnect
+  ([#60](https://github.com/jmcorgan/fips/issues/60)) and
+  `fipsctl` mesh-address rejection
+  ([#61](https://github.com/jmcorgan/fips/issues/61)).