Add LilyGo T-Echo-Card to the device hardware registry

[rcarteraz]

Adds the LilyGo T-Echo-Card to deviceHardwareList, keyed by T_ECHO_CARD = 136.

  {
    hwModel: 136,
    hwModelSlug: "T_ECHO_CARD",
    platformioTarget: "t-echo-card",
    architecture: "nrf52840",
    activelySupported: false,
    supportLevel: 1,
    displayName: "LilyGo T-Echo-Card",
    tags: ["LilyGo"],
  },

Review checklist:

• platformioTarget — derived from the slug; confirm against the firmware variant
• flip activelySupported / supportLevel when the web flasher should list it
• add images once the device SVG lands
• requiresDfu / partitionScheme if the platform needs them

Entry generated from the live mesh.proto and registry at generation time.