Collect findings from other people's writing, with sources

The skill so far only held what we broke ourselves. Most of what is worth
knowing about a new SDK is found rather than suffered — release notes,
other people's articles — and that deserves a place too, on terms that
stay fair to whoever wrote it.

So: entries in our own words, source named and linked, and the one thing
no external article can supply — what it would replace in our code and
whether it is genuinely a step forward. Attribution answers plagiarism,
not copyright, so nothing is pasted; an API signature is a fact, the
paragraph explaining it is not ours to take.

First four entries come from Natalia Panferova's writing at nilcoalescing
.com: the close button role and concentric corners, both of which replace
things we hand-built; ScrollPosition, which replaces one wrapper view;
and the iOS 27 toolbar APIs, which we cannot use at our deployment target
but which would delete a workaround the day we can.

A LICENSE was overdue and now says plainly what is ours, what is Apple's
and stays out of the repository, and what belongs to the authors we cite.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -4,7 +4,14 @@ A Claude Code plugin marketplace for Apple platform work.
 
 ## What is here
 
-**`pdat-swift-practice`** — one skill, `xcode-practice`. Practices for
+**`pdat-swift-practice`** — two skills.
+
+`apple-findings` is a curated file of APIs worth adopting that we found
+elsewhere: what each one is, what it would replace in our code, whether it
+is genuinely a step forward, and where we read about it. Written in our own
+words with sources named — see [Sourcing](#sourcing).
+
+`xcode-practice` is the opposite direction: practices for
 SwiftUI, Core Data, XcodeGen and Swift Testing that came out of shipping
 apps: work that must not happen in a view `body`, blobs that must stay off
 the main thread, derived collections computed once, Keychain access
@@ -57,7 +64,25 @@ Push a change, bump `version` in both `.claude-plugin/marketplace.json` and
 `pdat-swift-practice/.claude-plugin/plugin.json`, then `/plugin marketplace
 update` locally. Without the version bump, installs will not notice.
 
-## Adding to the skill
+## Sourcing
+
+`apple-findings` collects other people's discoveries, so it follows rules
+that keep it honest and lawful:
+
+- **Write the entry yourself.** An API signature is a fact and facts are
+  free to restate. The paragraph explaining it is the author's work, and
+  crediting them does not make copying it acceptable — attribution answers
+  plagiarism, not copyright.
+- **Name the source** — author, title, publication, date — and link it.
+  Partly courtesy, partly so a stale entry can be checked against the
+  original later.
+- **Say what it replaces in our code.** This is the half no external
+  article can write, and the reason the file is worth keeping at all.
+- **Prefer the vendor's own material where it exists.** When Apple's
+  shipped skills cover the same API, defer to them and keep only the
+  "what of ours does this replace" note.
+
+## Adding to `xcode-practice`
 
 The bar is deliberately high: something that actually went wrong, more than
 once, and whose fix is not obvious from the framework documentation. A rule