Adds CONTRIBUTING.md and link from README

…-code#5 §1)

New components/Vote/VoteControl.tsx: a hairline pill (up-chevron · net score ·
down-chevron, inline-SVG chevrons, tabular-nums). Up active → accent-soft, down
→ danger; hover previews the arrow colour; clicking the active arrow clears the
vote; stopPropagation so it never opens the row. Wired (reusing existing
mutations) into the feed card reaction bar (content.vote), discussion comments/
replies (discussion.vote), and the article reader footer (post/content vote) —
replacing the old "▲ helpful" upvote-only control. Outline variant only (the
prototype's tinted variant + tweaks panel are prototype-only). feed.spec updated
to the Upvote/Downvote labels.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

 §3)

New components/RichText/: useRichText hook + selection-aware markdown transforms
(bold/italic/strike/clear/link/ul/ol/quote/code/table), RichToolbar (inline ·
lists · block groups with dividers + "Switch to Markdown"), AaToggle, and
MdTextarea (autosize). Storage stays markdown; the toolbar wraps/inserts md
around the textarea selection (onMouseDown preventDefault keeps selection).

Replaces the TipTap comment/reply editor (deleted its Toolbar/useEditor/
extensions/help-modal) with this markdown composer — keeps the collapsed trigger
+ onSubmit(markdown)/submitLabel contract so DiscussionArea is unchanged — and
upgrades the ComposeModal body field. The TipTap article editor is untouched
(articles keep WYSIWYG). e2e comment-flow specs type into the new textarea.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…doff codu-code#5 §4)

New components/Celebrate/: Confetti (canvas burst, mint/status palette, ~1.7s,
early-returns under prefers-reduced-motion) and BadgeUnlock (full-screen dialog,
hexagon badge tile with codu-badge-pop + ring-pulse, "// badge unlocked", +points,
Keep browsing / See your badges → profile achievements). Fires once when the
real onboarding wins all complete — guarded by a localStorage flag (read via
useSyncExternalStore) + a close flag, trigger in an effect (no setState-in-effect).
username threaded through ShellActions for the badges link. Keyframes added to
globals (motion gated on prefers-reduced-motion).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Publications = feed sources, now followable. New publication_follow table
(userId↔sourceId, migration 0028) + publication tRPC router (getBySlug with
follower/article counts + isFollowing, follow/unfollow). The source profile at
/{slug} (_sourceProfileClient) is redesigned to the publication layout: square
logo tile, "// publication" eyebrow, name + @handle, Follow/Share, tagline,
Followers + Articles stats, "// latest articles" via UnifiedContentCard — no
banner. Byline "in {Publication}" links (card + reader MetaHeader) point to
/{slug}. (The /feed/[sourceSlug] route is 308-redirected to /{slug} by
next.config, so the canonical page lives there.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Remove redundant JSX banners, numbered group labels, and narration across the
recently-changed files; keep the WHY/gotchas/security rationale. Comments only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>