feat(NO-TASK): Allow the types the release-please standard sections

[aaronware]

Allows the commit types that @linchpinagency/release-please-config gives changelog sections to, and brings this repo's own release-please-config.json onto that standard.

Why wp-plugin and wp-theme have to be types

release-please groups changelog sections strictly by commit type. changelog-sections[].type is the only key its schema offers, and the schema is additionalProperties: false — there is no scope key.

So update(wp-plugin) and update(wp-theme) — the form renovatebot-config@652b5ad emits today — share the type update and collapse into a single changelog section. Promoting them to types gives WordPress plugins and themes a section each:

### WordPress Plugins 🔌
* **wporg:** Update akismet to v5.3
* **linchpin:** Update gravityforms to v3 - Major

### WordPress Themes 🖌️
* **deps:** Update ollie-pro to v2.6.1

The scope now names where the package came from: wporg for anything public (wp-packages.org and wpackagist.org are two routes to the same wordpress.org packages), linchpin for packagist.linchpin.com.

Why deps and platform are allowed

Not because Renovate emits them — it no longer does, routing that traffic through build(npm) and build(composer). They're allowed because the fleet's history contains ~150 such commits, and because either reads better than build for a hand-written dependency commit.

What changed

File	Why
index.js	TYPES gains deps, platform, wp-plugin, wp-theme; DEP_SCOPES gains wporg, linchpin
index.test.js	Covers the new types and scopes, and asserts a hyphenated type isn't truncated by the alternation
README.md	Documents the WordPress types and the wporg / linchpin distinction
release-please-config.json	Brought onto the shared standard

What this fixes

A crawl of 31 repos found the section lists and this type list had drifted apart in both directions:

• add and remove are valid types here but had no section anywhere — those commits were dropped from every changelog silently
• tweak had a section in 25 repos but was never a valid type, so no commit could reach it

release-please-config's test suite now asserts its section list equals this type list, so the two can't drift apart unnoticed again.

Review focus

index.js:3-15 — the type and scope lists, and whether deps/platform are worth keeping now that Renovate no longer emits them.

Both prefix forms lint, so PRs already open with update(wp-plugin) keep passing through the transition.