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-cosmos-rust/SKILL.md

@@ -0,0 +1,135 @@
+---
+name: azure-cosmos-rust
+description: |
+  Azure Cosmos DB SDK for Rust (NoSQL API). Use for document CRUD, queries, containers, and globally distributed data.
+  Triggers: "cosmos db rust", "CosmosClient rust", "container", "document rust", "NoSQL rust", "partition key".
+package: azure_data_cosmos
+---
+
+# Azure Cosmos DB SDK for Rust
+
+Client library for Azure Cosmos DB NoSQL API — globally distributed, multi-model database.
+
+## Installation
+
+```sh
+cargo add azure_data_cosmos azure_identity
+```
+
+## Environment Variables
+
+```bash
+COSMOS_ENDPOINT=https://<account>.documents.azure.com:443/
+COSMOS_DATABASE=mydb
+COSMOS_CONTAINER=mycontainer
+```
+
+## Authentication
+
+```rust
+use azure_identity::DeveloperToolsCredential;
+use azure_data_cosmos::CosmosClient;
+
+let credential = DeveloperToolsCredential::new(None)?;
+let client = CosmosClient::new(
+    "https://<account>.documents.azure.com:443/",
+    credential.clone(),
+    None,
+)?;
+```
+
+## Client Hierarchy
+
+| Client | Purpose | Get From |
+|--------|---------|----------|
+| `CosmosClient` | Account-level operations | Direct instantiation |
+| `DatabaseClient` | Database operations | `client.database_client()` |
+| `ContainerClient` | Container/item operations | `database.container_client()` |
+
+## Core Workflow
+
+### Get Database and Container Clients
+
+```rust
+let database = client.database_client("myDatabase");
+let container = database.container_client("myContainer");
+```
+
+### Create Item
+
+```rust
+use serde::{Serialize, Deserialize};
+
+#[derive(Serialize, Deserialize)]
+struct Item {
+    pub id: String,
+    pub partition_key: String,
+    pub value: String,
+}
+
+let item = Item {
+    id: "1".into(),
+    partition_key: "partition1".into(),
+    value: "hello".into(),
+};
+
+container.create_item("partition1", item, None).await?;
+```
+
+### Read Item
+
+```rust
+let response = container.read_item("partition1", "1", None).await?;
+let item: Item = response.into_model()?;
+```
+
+### Replace Item
+
+```rust
+let mut item: Item = container.read_item("partition1", "1", None).await?.into_model()?;
+item.value = "updated".into();
+
+container.replace_item("partition1", "1", item, None).await?;
+```
+
+### Patch Item
+
+```rust
+use azure_data_cosmos::models::PatchDocument;
+
+let patch = PatchDocument::default()
+    .with_add("/newField", "newValue")?
+    .with_remove("/oldField")?;
+
+container.patch_item("partition1", "1", patch, None).await?;
+```
+
+### Delete Item
+
+```rust
+container.delete_item("partition1", "1", None).await?;
+```
+
+## Key Auth (Optional)
+
+Enable key-based authentication with feature flag:
+
+```sh
+cargo add azure_data_cosmos --features key_auth
+```
+
+## Best Practices
+
+1. **Always specify partition key** — required for point reads and writes
+2. **Use `into_model()?`** — to deserialize responses into your types
+3. **Derive `Serialize` and `Deserialize`** — for all document types
+4. **Use Entra ID auth** — prefer `DeveloperToolsCredential` over key auth
+5. **Reuse client instances** — clients are thread-safe and reusable
+
+## Reference Links
+
+| Resource | Link |
+|----------|------|
+| API Reference | https://docs.rs/azure_data_cosmos |
+| Source Code | https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/cosmos/azure_data_cosmos |
+| crates.io | https://crates.io/crates/azure_data_cosmos |