refactor: flatten Microsoft skills from nested to flat directory structure

Rewrote sync_microsoft_skills.py (v4) to use each SKILL.md's frontmatter
'name' field as the flat directory name under skills/, replacing the nested
skills/official/microsoft/<lang>/<category>/<service>/ hierarchy.

This fixes CI failures caused by the indexing, validation, and catalog
scripts expecting skills/<id>/SKILL.md (depth 1).

Changes:
- Rewrite scripts/sync_microsoft_skills.py for flat output with collision detection
- Update scripts/tests/inspect_microsoft_repo.py for flat name mapping
- Update scripts/tests/test_comprehensive_coverage.py for name uniqueness checks
- Delete skills/official/ nested directory
- Add 129 Microsoft skills as flat directories (e.g. skills/azure-mgmt-botservice-dotnet/)
- Move attribution files to docs/ (LICENSE-MICROSOFT, microsoft-skills-attribution.json)
- Rebuild skills_index.json, CATALOG.md, README.md (845 total skills)

skills/azure-storage-blob-rust/SKILL.md

@@ -0,0 +1,132 @@
+---
+name: azure-storage-blob-rust
+description: |
+  Azure Blob Storage SDK for Rust. Use for uploading, downloading, and managing blobs and containers.
+  Triggers: "blob storage rust", "BlobClient rust", "upload blob rust", "download blob rust", "container rust".
+package: azure_storage_blob
+---
+
+# Azure Blob Storage SDK for Rust
+
+Client library for Azure Blob Storage — Microsoft's object storage solution for the cloud.
+
+## Installation
+
+```sh
+cargo add azure_storage_blob azure_identity
+```
+
+## Environment Variables
+
+```bash
+AZURE_STORAGE_ACCOUNT_NAME=<storage-account-name>
+# Endpoint: https://<account>.blob.core.windows.net/
+```
+
+## Authentication
+
+```rust
+use azure_identity::DeveloperToolsCredential;
+use azure_storage_blob::{BlobClient, BlobClientOptions};
+
+let credential = DeveloperToolsCredential::new(None)?;
+let blob_client = BlobClient::new(
+    "https://<account>.blob.core.windows.net/",
+    "container-name",
+    "blob-name",
+    Some(credential),
+    Some(BlobClientOptions::default()),
+)?;
+```
+
+## Client Types
+
+| Client | Purpose |
+|--------|---------|
+| `BlobServiceClient` | Account-level operations, list containers |
+| `BlobContainerClient` | Container operations, list blobs |
+| `BlobClient` | Individual blob operations |
+
+## Core Operations
+
+### Upload Blob
+
+```rust
+use azure_core::http::RequestContent;
+
+let data = b"hello world";
+blob_client
+    .upload(
+        RequestContent::from(data.to_vec()),
+        false,  // overwrite
+        u64::try_from(data.len())?,
+        None,
+    )
+    .await?;
+```
+
+### Download Blob
+
+```rust
+let response = blob_client.download(None).await?;
+let content = response.into_body().collect_bytes().await?;
+println!("Content: {:?}", content);
+```
+
+### Get Blob Properties
+
+```rust
+let properties = blob_client.get_properties(None).await?;
+println!("Content-Length: {:?}", properties.content_length);
+```
+
+### Delete Blob
+
+```rust
+blob_client.delete(None).await?;
+```
+
+## Container Operations
+
+```rust
+use azure_storage_blob::BlobContainerClient;
+
+let container_client = BlobContainerClient::new(
+    "https://<account>.blob.core.windows.net/",
+    "container-name",
+    Some(credential),
+    None,
+)?;
+
+// Create container
+container_client.create(None).await?;
+
+// List blobs
+let mut pager = container_client.list_blobs(None)?;
+while let Some(blob) = pager.try_next().await? {
+    println!("Blob: {}", blob.name);
+}
+```
+
+## Best Practices
+
+1. **Use Entra ID auth** — `DeveloperToolsCredential` for dev, `ManagedIdentityCredential` for production
+2. **Specify content length** — required for uploads
+3. **Use `RequestContent::from()`** — to wrap upload data
+4. **Handle async operations** — use `tokio` runtime
+5. **Check RBAC permissions** — ensure "Storage Blob Data Contributor" role
+
+## RBAC Permissions
+
+For Entra ID auth, assign one of these roles:
+- `Storage Blob Data Reader` — read-only
+- `Storage Blob Data Contributor` — read/write
+- `Storage Blob Data Owner` — full access including RBAC
+
+## Reference Links
+
+| Resource | Link |
+|----------|------|
+| API Reference | https://docs.rs/azure_storage_blob |
+| Source Code | https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/storage/azure_storage_blob |
+| crates.io | https://crates.io/crates/azure_storage_blob |