Add shared-slot nRF52 bootloader updates

scripts/nrf52_internal_bootloader_link.py

@@ -0,0 +1,56 @@
+"""Enable shared-slot internal bootloader update support on qualified nRF52840 targets.
+
+The bootloader package uses the ordinary bottom-aligned internal OTA store
+below 0xED000; no second linker reservation exists. This pre-script only binds
+the feature macro to the exact release inventory and fails closed if a target
+does not use the normal S140 v6/v7 1 MiB application layout.
+"""
+
+Import("env")
+
+import os
+from pathlib import Path
+
+
+inventory_path = Path(env["PROJECT_DIR"]) / "tools/mota/nrf52_internal_bootloader_targets.txt"
+try:
+    direct_targets = {
+        line.strip()
+        for line in inventory_path.read_text(encoding="utf-8").splitlines()
+        if line.strip() and not line.lstrip().startswith("#")
+    }
+except OSError as exc:
+    raise RuntimeError(f"cannot read nRF52 internal-bootloader inventory: {exc}")
+
+requested = (
+    os.environ.get("MESHCORE_NRF52_INTERNAL_BOOTLOADER_UPDATE") == "1"
+    or env["PIOENV"] in direct_targets
+)
+
+if requested:
+    # The macro is injected here so direct PIO and build.sh synthetic aliases
+    # cannot silently differ. Package admission is runtime-capacity based.
+    env.AppendUnique(CPPDEFINES=["OTA_INTERNAL_BOOTLOADER_UPDATE"])
+    board = env.BoardConfig()
+    # Most variants inherit the framework's top-level ``build.ldscript``.
+    # A few otherwise ordinary Adafruit nRF52840 boards (notably Keepteen LT1)
+    # declare it under ``build.arduino.ldscript`` instead.  Resolve both forms
+    # before making the safety decision; an unknown map still fails closed.
+    current = str(
+        board.get("build.ldscript", "")
+        or board.get("build.arduino.ldscript", "")
+    )
+    mcu = str(board.get("build.mcu", "")).lower()
+    if mcu != "nrf52840" or not (
+        current.endswith("nrf52840_s140_v6.ld")
+        or current.endswith("nrf52840_s140_v7.ld")
+    ):
+        raise RuntimeError(
+            "shared-slot bootloader update requires an nRF52840 with the normal "
+            f"S140 v6/v7 non-ExtraFS linker; found mcu={mcu or 'none'} "
+            f"linker={current or 'none'}"
+        )
+    print(
+        "nRF52 shared-slot bootloader update: normal linker %s; runtime EndF headroom required"
+        % current
+    )