feat: Add Official Microsoft & Gemini Skills (845+ Total)

🚀 Impact

Significantly expands the capabilities of **Antigravity Awesome Skills** by integrating official skill collections from **Microsoft** and **Google Gemini**. This update increases the total skill count to **845+**, making the library even more comprehensive for AI coding assistants.

✨ Key Changes

1. New Official Skills

- **Microsoft Skills**: Added a massive collection of official skills from [microsoft/skills](https://github.com/microsoft/skills).
  - Includes Azure, .NET, Python, TypeScript, and Semantic Kernel skills.
  - Preserves the original directory structure under `skills/official/microsoft/`.
  - Includes plugin skills from the `.github/plugins` directory.
- **Gemini Skills**: Added official Gemini API development skills under `skills/gemini-api-dev/`.

2. New Scripts & Tooling

- **`scripts/sync_microsoft_skills.py`**: A robust synchronization script that:
  - Clones the official Microsoft repository.
  - Preserves the original directory heirarchy.
  - Handles symlinks and plugin locations.
  - Generates attribution metadata.
- **`scripts/tests/inspect_microsoft_repo.py`**: Debug tool to inspect the remote repository structure.
- **`scripts/tests/test_comprehensive_coverage.py`**: Verification script to ensure 100% of skills are captured during sync.

3. Core Improvements

- **`scripts/generate_index.py`**: Enhanced frontmatter parsing to safely handle unquoted values containing `@` symbols and commas (fixing issues with some Microsoft skill descriptions).
- **`package.json`**: Added `sync:microsoft` and `sync:all-official` scripts for easy maintenance.

4. Documentation

- Updated `README.md` to reflect the new skill counts (845+) and added Microsoft/Gemini to the provider list.
- Updated `CATALOG.md` and `skills_index.json` with the new skills.

🧪 Verification

- Ran `scripts/tests/test_comprehensive_coverage.py` to verify all Microsoft skills are detected.
- Validated `generate_index.py` fixes by successfully indexing the new skills.

skills/official/microsoft/rust/entra/azure-identity-rust/SKILL.md

@@ -0,0 +1,115 @@
+---
+name: azure-identity-rust
+description: |
+  Azure Identity SDK for Rust authentication. Use for DeveloperToolsCredential, ManagedIdentityCredential, ClientSecretCredential, and token-based authentication.
+  Triggers: "azure-identity", "DeveloperToolsCredential", "authentication rust", "managed identity rust", "credential rust".
+package: azure_identity
+---
+
+# Azure Identity SDK for Rust
+
+Authentication library for Azure SDK clients using Microsoft Entra ID (formerly Azure AD).
+
+## Installation
+
+```sh
+cargo add azure_identity
+```
+
+## Environment Variables
+
+```bash
+# Service Principal (for production/CI)
+AZURE_TENANT_ID=<your-tenant-id>
+AZURE_CLIENT_ID=<your-client-id>
+AZURE_CLIENT_SECRET=<your-client-secret>
+
+# User-assigned Managed Identity (optional)
+AZURE_CLIENT_ID=<managed-identity-client-id>
+```
+
+## DeveloperToolsCredential
+
+The recommended credential for local development. Tries developer tools in order (Azure CLI, Azure Developer CLI):
+
+```rust
+use azure_identity::DeveloperToolsCredential;
+use azure_security_keyvault_secrets::SecretClient;
+
+let credential = DeveloperToolsCredential::new(None)?;
+let client = SecretClient::new(
+    "https://my-vault.vault.azure.net/",
+    credential.clone(),
+    None,
+)?;
+```
+
+### Credential Chain Order
+
+| Order | Credential | Environment |
+|-------|-----------|-------------|
+| 1 | AzureCliCredential | `az login` |
+| 2 | AzureDeveloperCliCredential | `azd auth login` |
+
+## Credential Types
+
+| Credential | Usage |
+|------------|-------|
+| `DeveloperToolsCredential` | Local development - tries CLI tools |
+| `ManagedIdentityCredential` | Azure VMs, App Service, Functions, AKS |
+| `WorkloadIdentityCredential` | Kubernetes workload identity |
+| `ClientSecretCredential` | Service principal with secret |
+| `ClientCertificateCredential` | Service principal with certificate |
+| `AzureCliCredential` | Direct Azure CLI auth |
+| `AzureDeveloperCliCredential` | Direct azd CLI auth |
+| `AzurePipelinesCredential` | Azure Pipelines service connection |
+| `ClientAssertionCredential` | Custom assertions (federated identity) |
+
+## ManagedIdentityCredential
+
+For Azure-hosted resources:
+
+```rust
+use azure_identity::ManagedIdentityCredential;
+
+// System-assigned managed identity
+let credential = ManagedIdentityCredential::new(None)?;
+
+// User-assigned managed identity
+let options = ManagedIdentityCredentialOptions {
+    client_id: Some("<user-assigned-mi-client-id>".into()),
+    ..Default::default()
+};
+let credential = ManagedIdentityCredential::new(Some(options))?;
+```
+
+## ClientSecretCredential
+
+For service principal with secret:
+
+```rust
+use azure_identity::ClientSecretCredential;
+
+let credential = ClientSecretCredential::new(
+    "<tenant-id>".into(),
+    "<client-id>".into(),
+    "<client-secret>".into(),
+    None,
+)?;
+```
+
+## Best Practices
+
+1. **Use `DeveloperToolsCredential` for local dev** — automatically picks up Azure CLI
+2. **Use `ManagedIdentityCredential` in production** — no secrets to manage
+3. **Clone credentials** — credentials are `Arc`-wrapped and cheap to clone
+4. **Reuse credential instances** — same credential can be used with multiple clients
+5. **Use `tokio` feature** — `cargo add azure_identity --features tokio`
+
+## Reference Links
+
+| Resource | Link |
+|----------|------|
+| API Reference | https://docs.rs/azure_identity |
+| Source Code | https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/identity/azure_identity |
+| crates.io | https://crates.io/crates/azure_identity |