Adopt inline 'Pro' badge on Pro-only section headings across the docs

[kilbot]

Summary

Add a consistent inline <span class="badge badge--primary">Pro</span> marker after section headings that describe Pro-only functionality, so readers get a fast visual cue without having to scan for an admonition block.

The pattern was used briefly in the v1.9 docs refresh and we liked it as a visual cue. Time to roll it out everywhere.

Why

We already mark Pro features two ways today:

• Pro Feature admonition (:::info Pro Feature …) — full callout, used at the top of Pro-only pages like customers/index.mdx, orders/index.mdx, coupons/index.mdx. Good for context, but a bit heavy for a sub-section on a mostly-free page.
• Inline text ("requires Pro", "with Pro you can…") — easy to miss when skimming.

The inline badge fills the gap between the two: tight enough to sit at the end of an ## Heading, loud enough to be unmissable. No custom CSS needed — badge badge--primary is a built-in Infima class shipped with Docusaurus.

Visual

```mdx

Coupon Codes Pro

```

Renders as: a small blue pill saying "Pro" at the end of the heading.

Scope — pages to apply the badge

Anywhere a sub-section on a page documents Pro-only behaviour. Suggested first pass (not exhaustive — anything new follows the same rule):

Pages that mix free and Pro content

These have free sections plus Pro sections — the inline badge belongs on the Pro headings:

• `products/index.mdx` — heading for the inline COGS editing section (already has a Pro admonition at L98; the heading itself should carry the badge)
• `payment/index.mdx` — heading for the additional gateways section
• `pos/checkout/index.mdx` — headings for additional gateways and the coupon-application section
• `settings/wp-admin/store-tax-ids.mdx` — heading for the per-store tax ID section
• `pos/cart/discounts.mdx` — any heading that links into the coupons workflow (currently links out to `/coupons` — could also badge the comparison table row label if we want)
• `getting-started/index.mdx` — the `## Pro Features` section heading (current at L130)
• `templates/index.mdx` — the `## Pro Features` section heading (current at L58)

Whole-page Pro features

Pages that are entirely Pro (already carry a `:::info Pro Feature` admonition near the top) — adding the badge to the page `# Title` would be redundant and ugly. Leave the title alone, keep the admonition, but use inline badges if any sub-section on that page documents a Pro-only sub-capability that goes beyond the page's headline scope.

Pages in this bucket:

• `customers/index.mdx`, `orders/index.mdx`, `reports/index.mdx`, `stores/index.mdx`, `coupons/index.mdx`, `extensions/index.mdx` — keep the existing admonition, don't double-mark the page title.

When to use the badge vs the admonition

Situation	Use
Whole page is Pro	:::info Pro Feature near the top, no inline badge on the title
Sub-section on a mixed page documents a Pro-only capability	Inline badge on the heading, no admonition (unless the section needs an explanatory note)
Sub-section needs both a visual cue and clarifying text	Inline badge on the heading plus a short :::note or :::info block with the detail

Acceptance criteria

• Audit versioned_docs/version-1.x/**/*.mdx for headings that describe Pro-only functionality on otherwise-free or mixed pages
• Add <span class="badge badge--primary">Pro</span> after each such heading
• Do not add the badge to page-level # Title headings on pages that already carry a :::info Pro Feature admonition
• Verify rendering in dev (pnpm start) — the badge should appear as a small blue pill at the end of the heading text, not on a new line
• Spot-check on mobile width — the heading should still wrap cleanly
• Update i18n/ translated copies (the badge syntax is HTML so it survives translation, but verify a few)

Out of scope

• Designing a new colour or variant for the badge — we're using Docusaurus' default badge--primary
• Renaming any existing :::info Pro Feature admonitions to use the badge instead — those stay as page-level callouts
• Adding the badge to v0.4.x docs (legacy, frozen)

Reference example

Used in PR #188 (now removed during page restructure): the heading ## Coupon Codes <span class="badge badge--primary">Pro</span> rendered nicely as a visual cue. Bring it back, but everywhere it makes sense.