feat: Initial agent-skills repo — 4 adapted skills for Mosaic Stack

Skills included:
- pr-reviewer: Adapted for Gitea/GitHub via platform-aware scripts
  (dropped fetch_pr_data.py and add_inline_comment.py, kept generate_review_files.py)
- code-review-excellence: Methodology and checklists (React, TS, Python, etc.)
- vercel-react-best-practices: 57 rules for React/Next.js performance
- tailwind-design-system: Tailwind CSS v4 patterns, CVA, design tokens

New shell scripts added to ~/.claude/scripts/git/:
- pr-diff.sh: Get PR diff (GitHub gh / Gitea API)
- pr-metadata.sh: Get PR metadata as normalized JSON

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/code-review-excellence/reference/qt.md

@@ -0,0 +1,186 @@
+# Qt Code Review Guide
+
+> Code review guidelines focusing on object model, signals/slots, event loop, and GUI performance. Examples based on Qt 5.15 / Qt 6.
+
+## Table of Contents
+
+- [Object Model & Memory Management](#object-model--memory-management)
+- [Signals & Slots](#signals--slots)
+- [Containers & Strings](#containers--strings)
+- [Threads & Concurrency](#threads--concurrency)
+- [GUI & Widgets](#gui--widgets)
+- [Meta-Object System](#meta-object-system)
+- [Review Checklist](#review-checklist)
+
+---
+
+## Object Model & Memory Management
+
+### Use Parent-Child Ownership Mechanism
+Qt's `QObject` hierarchy automatically manages memory. For `QObject`, prefer setting a parent object over manual `delete` or smart pointers.
+
+```cpp
+// ❌ Manual management prone to memory leaks
+QWidget* w = new QWidget();
+QLabel* l = new QLabel();
+l->setParent(w);
+// ... If w is deleted, l is automatically deleted. But if w leaks, l also leaks.
+
+// ✅ Specify parent in constructor
+QWidget* w = new QWidget(this); // Owned by 'this'
+QLabel* l = new QLabel(w);      // Owned by 'w'
+```
+
+### Use Smart Pointers with QObject
+If a `QObject` has no parent, use `QScopedPointer` or `std::unique_ptr` with a custom deleter (use `deleteLater` if cross-thread). Avoid `std::shared_ptr` for `QObject` unless necessary, as it confuses the parent-child ownership system.
+
+```cpp
+// ✅ Scoped pointer for local/member QObject without parent
+QScopedPointer<MyObject> obj(new MyObject());
+
+// ✅ Safe pointer to prevent dangling pointers
+QPointer<MyObject> safePtr = obj.data();
+if (safePtr) {
+    safePtr->doSomething();
+}
+```
+
+### Use `deleteLater()`
+For asynchronous deletion, especially in slots or event handlers, use `deleteLater()` instead of `delete` to ensure pending events in the event loop are processed.
+
+---
+
+## Signals & Slots
+
+### Prefer Function Pointer Syntax
+Use compile-time checked syntax (Qt 5+).
+
+```cpp
+// ❌ String-based (runtime check only, slower)
+connect(sender, SIGNAL(valueChanged(int)), receiver, SLOT(updateValue(int)));
+
+// ✅ Compile-time check
+connect(sender, &Sender::valueChanged, receiver, &Receiver::updateValue);
+```
+
+### Connection Types
+Be explicit or aware of connection types when crossing threads.
+- `Qt::AutoConnection` (Default): Direct if same thread, Queued if different thread.
+- `Qt::QueuedConnection`: Always posts event (thread-safe across threads).
+- `Qt::DirectConnection`: Immediate call (dangerous if accessing non-thread-safe data across threads).
+
+### Avoid Loops
+Check logic that might cause infinite signal loops (e.g., `valueChanged` -> `setValue` -> `valueChanged`). Block signals or check for equality before setting values.
+
+```cpp
+void MyClass::setValue(int v) {
+    if (m_value == v) return; // ? Good: Break loop
+    m_value = v;
+    emit valueChanged(v);
+}
+```
+
+---
+
+## Containers & Strings
+
+### QString Efficiency
+- Use `QStringLiteral("...")` for compile-time string creation to avoid runtime allocation.
+- Use `QLatin1String` for comparison with ASCII literals (in Qt 5).
+- Prefer `arg()` for formatting (or `QStringBuilder`'s `%` operator).
+
+```cpp
+// ❌ Runtime conversion
+if (str == "test") ...
+
+// ✅ Prefer QLatin1String for comparison with ASCII literals (in Qt 5)
+if (str == QLatin1String("test")) ... // Qt 5
+if (str == u"test"_s) ...             // Qt 6
+```
+
+### Container Selection
+- **Qt 6**: `QList` is now the default choice (unified with `QVector`).
+- **Qt 5**: Prefer `QVector` over `QList` for contiguous memory and cache performance, unless stable references are needed.
+- Be aware of Implicit Sharing (Copy-on-Write). Passing containers by value is cheap *until* modified. Use `const &` for read-only access.
+
+```cpp
+// ❌ Forces deep copy if function modifies 'list'
+void process(QVector<int> list) {
+    list[0] = 1; 
+}
+
+// ✅ Read-only reference
+void process(const QVector<int>& list) { ... }
+```
+
+---
+
+## Threads & Concurrency
+
+### Subclassing QThread vs Worker Object
+Prefer the "Worker Object" pattern over subclassing `QThread` implementation details.
+
+```cpp
+// ❌ Business logic inside QThread::run()
+class MyThread : public QThread {
+    void run() override { ... } 
+};
+
+// ✅ Worker object moved to thread
+QThread* thread = new QThread;
+Worker* worker = new Worker;
+worker->moveToThread(thread);
+connect(thread, &QThread::started, worker, &Worker::process);
+thread->start();
+```
+
+### GUI Thread Safety
+**NEVER** access UI widgets (`QWidget` and subclasses) from a background thread. Use signals/slots to communicate updates to the main thread.
+
+---
+
+## GUI & Widgets
+
+### Logic Separation
+Keep business logic out of UI classes (`MainWindow`, `Dialog`). UI classes should only handle display and user input forwarding.
+
+### Layouts
+Avoid fixed sizes (`setGeometry`, `resize`). Use layouts (`QVBoxLayout`, `QGridLayout`) to handle different DPIs and window resizing gracefully.
+
+### Blocking Event Loop
+Never execute long-running operations on the main thread (freezes GUI).
+- **Bad**: `Sleep()`, `while(busy)`, synchronous network calls.
+- **Good**: `QProcess`, `QThread`, `QtConcurrent`, or asynchronous APIs (`QNetworkAccessManager`).
+
+---
+
+## Meta-Object System
+
+### Properties & Enums
+Use `Q_PROPERTY` for values exposed to QML or needing introspection.
+Use `Q_ENUM` to enable string conversion for enums.
+
+```cpp
+class MyObject : public QObject {
+    Q_OBJECT
+    Q_PROPERTY(int value READ value WRITE setValue NOTIFY valueChanged)
+public:
+    enum State { Idle, Running };
+    Q_ENUM(State)
+    // ...
+};
+```
+
+### qobject_cast
+Use `qobject_cast<T*>` for QObjects instead of `dynamic_cast`. It is faster and doesn't require RTTI.
+
+---
+
+## Review Checklist
+
+- [ ] **Memory**: Is parent-child relationship correct? Are dangling pointers avoided (using `QPointer`)?
+- [ ] **Signals**: Are connections checked? Do lambdas use safe captures (context object)?
+- [ ] **Threads**: Is UI accessed only from main thread? Are long tasks offloaded?
+- [ ] **Strings**: Are `QStringLiteral` or `tr()` used appropriately?
+- [ ] **Style**: Naming conventions (camelCase for methods, PascalCase for classes).
+- [ ] **Resources**: Are resources (images, styles) loaded from `.qrc`?