[alexkorotysh]

Summary

Reworks the Telegram bridge message layout and fixes channel names always
showing "LongFast", even for non-primary channels or when the mesh actually
uses a different preset.

Changes

• New message format:

👤 Name (node id) - Channel
📶 Signal: SNR: X dB / RSSI: -X dBm

💬 Text: message

replacing the old Name → Channel / inline-metadata layout.

• channelName() no longer hardcodes "LongFast" for channel 0 — it now
  falls back to "Primary" (channel 0) or "Ch N" (others) when no name is
  configured.
• New telegram.channel_names config option (internal/config/config.go,
  documented in config.example.toml) lets you name channels shown in
  forwarded messages, e.g.:

  [telegram.channel_names]
  0 = "MediumFast"
  1 = "Admin"

FYI

Intentionally skipped auto-detecting the channel name/preset from the node
via protobuf (parsing the config cache, LoRa modem preset, etc.) — that
would've added unnecessary complexity (pb/proto imports in the telegram
package, wiring configCache into Bot, live-config parsing). Went with a
simple manual telegram.channel_names mapping instead — good enough for
the job.