Release 1.2.1: README rewrite, popover scroll fix, and post-RMQ cleanup

[onemli]

Three things in one release, all small, all independent:

README rewrite

The previous README leaned on marketing-style summaries and three layered architecture sections that nobody scrolled to. The rewrite trims that down: a short "Why this exists" paragraph that talks about the actual operator pain (the moquery folder, the Postman collection, the spreadsheets), a tighter "What it does" list with five concrete categories, a four-command quickstart, and a single architecture image with a stack table. About a third shorter overall.

Popover scroll fix

The package picker that opens from the Class Browser dialog had a broken mouse-wheel scroll. Drag worked, wheel didn't.

Root cause was a layering issue between two libraries:

1. Radix Dialog (which ClassBrowserDialog uses) wraps its content in react-remove-scroll. That installs a document-level wheel event listener and calls preventDefault() on wheel events targeting anything outside the dialog's content subtree or its shards array.
2. Radix Popover Content (which PackageCombobox uses, via the shadcn wrapper) is rendered through PopoverPrimitive.Portal into document.body. That puts the popover body outside the dialog's content DOM and outside its shards.
3. Wheel events fired on the popover list therefore got caught by the dialog's removal-scroll listener and cancelled before browser-native scroll could kick in.

The shadcn popover.tsx wrapper now accepts an opt-in withoutPortal prop. PackageCombobox uses it so the popover renders inline inside the dialog content, which makes the dialog's scroll lock recognise it as a child and let wheel events through. Other call sites of PopoverContent are unaffected because the prop defaults to false.

Frontend cleanup

services/ai.ts carried three stubs (generateQuery, getSuggestions, submitFeedback) that posted to backend endpoints which were never wired up (/api/ai/generate/, /generate/suggest/, /generate/feedback/). The only callers were the matching test cases. Removed both. Five orphan response types (AIGenerateResponse, AISuggestResponse, AIGeneratedNode/Filter/Edge) went with them.

Also dropped three stale "advisor" mentions in the loader_v2 docstring that referred to a feature that was never built.

Architecture diagram

frontend/src/assets/architecture.mmd is updated to match the post-RMQ topology (no event-bus node, AWX webhook arrow points at the backend, separate edge for the 30-second beat poll). The rendered SVG is committed alongside the source so the repo stays self-consistent with what docs.fabrikops.com serves.

Verification

• TypeScript: npx tsc --noEmit clean
• Popover fix: tested in Class Browser dialog with the rebuilt frontend container; mouse wheel scrolls the "All packages (A–Z)" list as expected
• README rendered correctly on GitHub preview