tools: cull to a minimal user-facing set

Reduce tools/ to the four scripts an outside contributor needs: build,
verify, flash, and size-profile. Drop maintainer-only workflow scripts
(sibling-repo pulls, firmware-archive auto-commit, version tagging),
broken stubs (doxygen.sh, variables.sh), and the entire tools/2024/
directory.

tools/2024/ included a 647 KB Arduino.tar.gz bundling 20 third-party
Arduino libraries (RadioHead = GPLv2, TinyGPSPlus = LGPL, etc.) without
per-library attribution in NOTICE; a 503 KB GPL avrdude.conf; the GPL
Optiboot bootloader hex; and pre-built firmware/test binaries. Users
install the libraries via Arduino Library Manager (per README), use the
system avrdude, and reproduce the firmware from source.

README.md: add EEPROMEx to the library list (used by WII5Config /
WII5Sh3dConfig); note that RadioHead is GPLv2 dual-licensed and only
LoRa builds (-DWII5_RADIO_LORA) link it.

CONTRIBUTING.md: replace the dead tools/upload.sh reference with the
generic *.local.sh pattern.

Kept: build_local.sh, verify.sh, icsp.sh, memory.pl.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CONTRIBUTING.md

@@ -18,9 +18,9 @@ short up-front conversation usually saves a long review.
 This is an Arduino IDE / `arduino-cli` project targeting the
 ATmega2560 on a custom WII5 v2 board (see `WII5_board_v2.h`).
 
-The build scripts in `tools/` are parameterized via env vars; copy
-`tools/upload.sh` to `tools/upload.local.sh` (gitignored) and edit, or
-export `WII5_BUILD_DIR`, `WII5_AVRDUDE_CONF`, `WII5_REMOTE`, etc. as needed.
+The build scripts in `tools/` are parameterized via env vars; copy any
+of them to `tools/<name>.local.sh` (gitignored) and edit, or export
+`WII5_BUILD_DIR`, `WII5_AVRDUDE_CONF`, `WII5_SERIAL`, etc. as needed.
 See each script's preamble for the env vars it expects.
 
 ## Submitting changes