Move development scripts into development/, leaving scripts/ plugin-only

The root scripts/ folder now holds only download_bin.vim, the one script
the plugin itself invokes (via :NuwikiInstall and the vim-plug/Dein build
hooks). All developer tooling — the start-nvim/start-vim launchers,
test-personal-wiki, the keymap harnesses, and syntax-diag — moves to
development/ alongside the developer docs.

REPO_ROOT resolution is unchanged (development/ sits one level under root,
same as scripts/ did); only the explicit cross-references, the CI harness
invocations, the README launcher paths, and the ONBOARDING structure tree
are updated.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

development/test-personal-wiki.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+#
+# test-personal-wiki.sh — open the user's real personal wiki via start-vim.sh.
+#
+# Reuses start-vim.sh's plumbing (binary build, vim-lsp clone, viminfo
+# under the dev cache) but points the wiki root at ~/.vimwiki/personal_wiki
+# and disables seed_wiki so we don't drop a scratch `Notes.wiki` into your
+# real notes.
+#
+# Useful when reproducing a user-reported bug against actual content rather
+# than the seeded smoke-test wiki. State (viminfo/sessions) still lives
+# under $XDG_CACHE_HOME/nuwiki-dev/ so your real Vim install stays untouched.
+#
+# Usage:
+#   ./development/test-personal-wiki.sh                          # open index.wiki
+#   ./development/test-personal-wiki.sh path/to/note.wiki        # open a specific file
+#   NUWIKI_PERSONAL_WIKI=/other/path ./development/test-personal-wiki.sh
+#   NUWIKI_DEV_SKIP_BUILD=1 ./development/test-personal-wiki.sh  # reuse the cached binary
+
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+WIKI_DIR="${NUWIKI_PERSONAL_WIKI:-$HOME/.vimwiki/personal_wiki}"
+
+if [[ ! -d "$WIKI_DIR" ]]; then
+  echo "test-personal-wiki: $WIKI_DIR does not exist" >&2
+  echo "set NUWIKI_PERSONAL_WIKI to point at your wiki, or create the default path" >&2
+  exit 1
+fi
+
+export NUWIKI_DEV_WIKI="$WIKI_DIR"
+export NUWIKI_DEV_NO_SEED=1
+
+exec "$REPO_ROOT/development/start-vim.sh" "$@"