feat: Phase 1 firmware — time-multiplexed tri-protocol RX scanner

First Phase 1 increment toward the single-device 3-in-1: one Heltec V3
(ESP32-S3 + single SX1262) rotating the radio through the Meshtastic /
MeshCore / Reticulum PHY presets, logging every raw packet it demodulates
per dwell window. No framing/crypto/bridge yet — proves the RX loop first.

Validated on hardware: radio.begin() clean, all three presets cycle, and
the Meshtastic window received live broadcast packets (-36..-41 dBm). The
single-radio time-multiplex premise (ARCHITECTURE.md §2) holds.

MeshCore sync word and Reticulum PHY are flagged placeholders in CONFIGS[].
Deps pinned (espressif32 7.0.1, RadioLib 7.7.1). Adds venv/pycache/storage
to .gitignore.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

firmware/platformio.ini

@@ -0,0 +1,18 @@
+; archy-messh Phase 1 firmware — single Heltec WiFi LoRa 32 V3, one SX1262
+; time-multiplexed across the Meshtastic / MeshCore / Reticulum PHY configs.
+;
+; See ../docs/ARCHITECTURE.md §2-§3 for why Phase 1 is a single time-multiplexed
+; radio (Option A) rather than the 3-separate-boards host bridge of Phase 0.
+;
+; Versions pinned exactly — do not float.
+
+[env:heltec_wifi_lora_32_V3]
+platform = platformio/espressif32@7.0.1
+board = heltec_wifi_lora_32_V3
+framework = arduino
+monitor_speed = 115200
+monitor_filters = time, default
+build_flags =
+    -D ARCHY_MESSH_FW
+lib_deps =
+    jgromes/RadioLib@7.7.1