docs: restructure README around what the project actually does differently (v0.23.3-beta)

Documentation only — no functional change.

The previous README opened with eighty lines of screenshots before saying what the
software was, then listed twenty-five feature sections in no particular order.
Change Guard — the one capability nothing else in this space has — sat fifth, under
a heading that gave no hint of it.

Reordered around the questions a new visitor actually asks:

  what is it → why is it different → show me → how do I run it → full features
  → reference

"What makes it different" now leads with the problem rather than the feature: that
RouterOS applies every command immediately, with no transaction and no cross-object
validation, and that MikroTik's own documented advice for VLAN filtering is to have
a serial console ready. Change Guard, lockout prediction and Config Health follow as
answers to it, with the verified auto-revert timeline and a real prediction warning
quoted rather than described.

The twenty-five flat sections are grouped into seven, safety first. Reference
material — environment variables, Change Guard settings, secret management, OIDC
setup, tech stack, project layout — is consolidated at the end instead of being
interleaved with features, and the deepest auto-revert mechanics move into a
collapsible block: present for anyone relying on it, out of the way of a skim.

Added a table of contents; the document was seven hundred lines with no navigation.
Headings that anchors point at use "and" rather than an ampersand, because GitHub
slugifies an entity into a double hyphen and six links would have broken silently.

No content dropped: every feature, table and screenshot from the previous version is
still present, verified by keyword and image-path comparison. 713 lines to 573,
entirely from removing repetition.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-backend",
-  "version": "0.23.2-beta",
+  "version": "0.23.3-beta",
   "description": "Mikrotik Network Management Platform - Backend API",
   "main": "dist/index.js",
   "scripts": {

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-frontend",
-  "version": "0.23.2-beta",
+  "version": "0.23.3-beta",
   "private": true,
   "type": "module",
   "scripts": {

frontend/src/version.ts

@@ -1 +1 @@
-export const APP_VERSION = 'v0.23.2 Beta';
+export const APP_VERSION = 'v0.23.3 Beta';