fix(mesh): Meshtastic 3ccc pkc_capable pill + Sideband image interop + critical CBOR wire-bloat fix

Merges in the meshtastic agent's now-finished work alongside this session's
continuation: stock-peer (3ccc) PKI-capability is now stamped through
get_contacts -> refresh_contacts -> MeshPeer.pkc_capable, so a directed DM to/from
a PKC-capable stock Meshtastic peer correctly shows the E2E pill on the Sent row,
not just received messages. Confirmed live: .198 sees "Meshtastic 3ccc" with
pkc_capable=true.

Also fixes two real interop/correctness bugs found while live-testing the
Reticulum <-> Sideband link:
  - Receive: the daemon only ever read LXMF's plain-text content, silently
    dropping native FIELD_IMAGE/FIELD_FILE_ATTACHMENTS fields — a stock
    Sideband/NomadNet photo vanished into a blank-space message. Now decoded
    into the same ContentInline typed envelope our own attachments use.
  - Send: images to a non-archy (stock) peer now use native LXMF FIELD_IMAGE
    instead of our own opaque CBOR wire format, which Sideband can't decode.
  - Root cause of a garbled MC-chunk-fragment bug: TypedEnvelope.v/.sig (the
    OUTER wrapper every message type uses) serialized raw bytes as a CBOR
    array-of-integers instead of a native byte string, bloating every
    message on the wire ~2-3.5x — enough to push even a tiny ReadReceipt
    over the 140-byte single-frame chunking threshold. Root-caused by
    reading ciborium's deserializer source directly (deserialize_bytes only
    works within its internal scratch buffer; deserialize_byte_buf streams
    unbounded).

Frontend: consolidated the attach/record buttons into a single animated "+"
menu (was overflowing the compose row).

857/857 tests pass. Verified live across all 5 deploy-roster nodes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

core/archipelago/src/mesh/protocol.rs

@@ -391,6 +391,11 @@ pub struct ParsedContact {
     pub contact_type: u8,
     pub path_len: u8,
     pub flags: u8,
+    /// Whether this contact is end-to-end (PKI / Curve25519) capable. Only the
+    /// Meshtastic adapter sets this (true once we've learned the peer's real
+    /// NodeInfo public key, so the firmware delivers DMs PKC-encrypted). Meshcore
+    /// contacts leave it `false` — their E2E status is tracked per-message.
+    pub pkc_capable: bool,
 }
 
 /// Parse RESP_CONTACT (0x03) response.
@@ -433,6 +438,8 @@ pub fn parse_contact(data: &[u8]) -> Result<ParsedContact> {
         contact_type,
         path_len,
         flags,
+        // Meshcore tracks E2E per message, not per contact.
+        pkc_capable: false,
     })
 }