feat(build): configure project tooling and update dependencies

- Replace placeholder deps with click, pygnmi, and rich for CLI functionality
- Add fabric-orch CLI entry point via project.scripts
- Configure hatchling as build backend with wheel/sdist targets
- Add ruff linter configuration for code quality
- Add dev dependency group with ruff
- Alphabetize yang module imports

src/gnmi/README.md

@@ -0,0 +1,183 @@
+# gNMI Client Module
+
+This module provides a high-level gNMI client wrapper for interacting with Arista devices using pygnmi.
+
+## Features
+
+- Connection management with context manager support
+- Get capabilities (list supported YANG models)
+- Get configuration and state data at any YANG path
+- Set configuration with dry-run support
+- Subscribe to path updates (on-change, sample modes)
+- Error handling with meaningful exceptions
+
+## Installation
+
+Ensure you have the required dependencies:
+
+```bash
+uv add pygnmi click rich
+```
+
+## Usage
+
+### Basic Connection
+
+```python
+from gnmi import GNMIClient
+
+# Using context manager (recommended)
+with GNMIClient(
+    host="172.16.0.50",
+    port=6030,
+    username="admin",
+    password="admin",
+    insecure=True
+) as client:
+    # Use the client
+    caps = client.capabilities()
+    print(caps)
+```
+
+### Get Capabilities
+
+```python
+with GNMIClient(host="172.16.0.50", port=6030) as client:
+    # Get raw capabilities
+    caps = client.capabilities()
+    print(f"gNMI Version: {caps['gnmi_version']}")
+    
+    # Get parsed models
+    models = client.get_models()
+    for model in models:
+        print(f"  {model.name} ({model.organization}) v{model.version}")
+```
+
+### Get Data
+
+```python
+with GNMIClient(host="172.16.0.50", port=6030) as client:
+    # Get all data (config + state)
+    result = client.get("/interfaces/interface[name=Ethernet1]")
+    
+    # Get config only
+    result = client.get(
+        "/interfaces/interface[name=Ethernet1]",
+        data_type="config"
+    )
+    
+    # Get state only
+    result = client.get(
+        "/interfaces/interface[name=Ethernet1]/state",
+        data_type="state"
+    )
+    
+    # Get multiple paths
+    result = client.get([
+        "/interfaces/interface[name=Ethernet1]/state",
+        "/interfaces/interface[name=Ethernet2]/state",
+    ])
+```
+
+### Set Configuration
+
+```python
+with GNMIClient(host="172.16.0.50", port=6030) as client:
+    # Dry-run (default) - shows what would be set
+    result = client.set(
+        path="/interfaces/interface[name=Ethernet1]/config/description",
+        value="Uplink to Spine",
+        dry_run=True
+    )
+    
+    # Actually apply the change
+    result = client.set(
+        path="/interfaces/interface[name=Ethernet1]/config/description",
+        value="Uplink to Spine",
+        dry_run=False
+    )
+    
+    # Replace operation
+    result = client.set(
+        path="/interfaces/interface[name=Ethernet1]/config",
+        value={"description": "New config", "enabled": True},
+        operation="replace",
+        dry_run=False
+    )
+    
+    # Delete operation
+    result = client.set(
+        path="/interfaces/interface[name=Ethernet1]/config/description",
+        value=None,
+        operation="delete",
+        dry_run=False
+    )
+```
+
+### Subscribe to Updates
+
+```python
+with GNMIClient(host="172.16.0.50", port=6030) as client:
+    # Subscribe to interface state changes
+    subscription = client.subscribe(
+        paths="/interfaces/interface/state/oper-status",
+        mode="stream",
+        stream_mode="on-change"
+    )
+    
+    # Process updates
+    for update in subscription:
+        print(update)
+```
+
+## Error Handling
+
+The module provides specific exceptions for different error types:
+
+```python
+from gnmi import GNMIClient, GNMIError, GNMIConnectionError, GNMIPathError
+
+try:
+    with GNMIClient(host="172.16.0.50", port=6030) as client:
+        result = client.get("/invalid/path")
+except GNMIConnectionError as e:
+    print(f"Connection failed: {e}")
+except GNMIPathError as e:
+    print(f"Invalid path: {e}")
+except GNMIError as e:
+    print(f"gNMI error: {e}")
+```
+
+## Environment Variables
+
+The CLI supports these environment variables for defaults:
+
+- `GNMI_TARGET` - Target device (host:port)
+- `GNMI_USERNAME` - Username for authentication
+- `GNMI_PASSWORD` - Password for authentication
+
+## Path Format Notes
+
+For Arista EOS, use native paths **without** module prefixes for subscriptions:
+
+```python
+# ✅ Correct - native path
+"/interfaces/interface[name=Ethernet1]/state"
+
+# ❌ Incorrect - with module prefix (may fail for subscriptions)
+"/openconfig-interfaces:interfaces/interface[name=Ethernet1]/state"
+```
+
+## Validated Paths
+
+These paths have been validated against Arista cEOS 4.35.0F:
+
+| Category | Path | Notes |
+|----------|------|-------|
+| Interfaces | `/interfaces/interface[name=Ethernet1]/state` | Full state |
+| BGP | `/network-instances/network-instance[name=default]/protocols/protocol[identifier=BGP][name=BGP]/bgp/neighbors/neighbor/state` | All neighbors |
+| VXLAN | `/interfaces/interface[name=Vxlan1]/arista-vxlan/vlan-to-vnis` | VNI mappings |
+| MLAG | `/arista/eos/mlag/config` | Config only |
+| EVPN | `/arista/eos/evpn` | Config only |
+
+See `docs/yang-paths.md` for complete path documentation.