fix(e2ee): location message decryption (AAD contentType, isSelf, key pinning)

[nezumi0627]

Summary

decryptE2EELocationMessage could never successfully decrypt a received E2EE location message, for two independent reasons:

1. AAD content type: string "LOCATION" → NaN → 0 (≠ 15)

Incoming messages carry the enum name ("LOCATION") because rename_thrift maps numeric enums back to strings. The encrypt side hardcodes the correct value in the AAD:

// encryptE2EELocationMessage
const aad = this.generateAAD(to, _from, senderKeyId, receiverKeyId, specVersion, 15);

but the decrypt path passed messageObj.contentType straight through as contentType as number. getIntBytes("LOCATION") → setInt32(0, NaN) → writes 0, so the decryptor built an AAD with f = 0 while the ciphertext was authenticated with f = 15 — GCM auth verification always failed. The retry block then retried with identical inputs and rethrew.

decryptE2EEDataMessage already handles this correctly (LINETypes.enums.ContentType[messageObj.contentType]); the location path now does the same.

2. isSelf defaulted to true and was never derived

Unlike decryptE2EETextMessage / decryptE2EEDataMessage, the location path never checked _from === profile.mid, and its default parameter was true. The only caller (decryptE2EEMessage) passes no isSelf, so every location message was treated as self-sent: for a received 1:1 message it fetched my own public key via getE2EELocalPublicKey(to=myMid, …) and computed ECDH(myPriv, myPub) instead of ECDH(myPriv, senderPub) — always the wrong shared secret.

It also never pinned the self private key by envelope key id (#88), so it additionally broke on key rotation — exactly what #88 fixed for the text/data paths. The function now mirrors those two:

• isSelf = false default, derived from from === profile.mid
• self-key pinned by senderKeyId/receiverKeyId with latest-key fallback
• peer key looked up as (to, receiverKeyId) when self-sent, (_from, senderKeyId) when received

Testing

• New location_decrypt.test.ts (same trap-the-primitive approach as key_selection.test.ts), 3 cases:
  • received: AAD contentType is numeric 15, self-key pinned by receiverKeyId, peer pubKey looked up as (_from, senderKeyId)
  • self-sent: isSelf derived from mid, peer pubKey looked up as (to, receiverKeyId)
  • by-id miss falls back to latest key
• Full suite: deno test --allow-all — 217 passed, 0 failed.