chore(main): release 0.39.0

[github-actions]

🤖 I have created a release beep boop

0.39.0 (2026-06-15)

Features

• derp: honor the server's advertised send rate-limit (#249) (c04e70c)
• magicsock: ping immediately on CallMeMaybe, bypassing the discovery floor (#246) (cd4beb4)
• runtime: stop the periodic STUN sweep while there are no peers (#247) (e2eaf0f)

Bug Fixes

• control-serde: serialize ProtoPortRange as Go's TextMarshaler string (#245) (753de69)
• control: full Hostinfo on side-command requests + fix stale STUN test (#244) (1b8917e)
• dataplane: handle IPv4 fragments like Go decode4 + filter pre() (#253) (a2fd8fa)
• dns: echo RD + set RA and only compress multi-answer names, matching Go (#242) (59bc54c)
• magic-dns: SERVFAIL not NXDOMAIN when an off-tailnet name can't be forwarded (#248) (a8efb90)
• magicsock: send SOFTWARE+FINGERPRINT on STUN binding request to match Go (#241) (d970570)

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[github-actions]

🤖 Created releases:

• v0.39.0

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