feat(cli): add nemo-flow plugins edit (NVIDIA#98)

#### Overview

Adds a plugin-driven observability configuration flow centered on `plugins.toml`, including an interactive editor for the built-in Observability component and a clean removal of legacy exporter configuration surfaces.

- [x] I confirm this contribution is my own work, or I have the right to submit it under this project's license.
- [x] I searched existing issues and open pull requests, and this does not duplicate existing work.

#### Details

- Adds `nemo-flow plugins edit` with user/project/global scope handling, keyboard-driven menus, preview, save, reset, clear, and schema/type-backed editor metadata from core config types.
- Moves gateway observability setup to plugin activation from `plugins.toml`, removes legacy exporter flags/config parsing, and updates doctor/setup/session handling accordingly.
- Canonicalizes plugin config discovery around `plugins.toml`, including layered system/project/user merge behavior, duplicate component-kind checks, and clearer legacy config errors.
- Adds comprehensive docs for plugin configuration file behavior and updates coding-agent observability docs and examples.
- Adds Rust and CLI coverage for Observability schema/editor behavior, plugin config path resolution and merge semantics, doctor reporting, and legacy config removal.

Validation run locally:

- `cargo fmt --check`
- `cargo clippy -p nemo-flow-cli -- -D warnings`
- `cargo test -p nemo-flow-cli`
- `cargo test -p nemo-flow --features schema`
- `just docs`
- `just test-rust`

#### Where should the reviewer start?

Start with `crates/cli/src/plugins.rs` for the interactive `plugins.toml` editor, then review `crates/cli/src/config.rs` for plugin file discovery and merge behavior, and `docs/build-plugins/plugin-configuration-files.md` for the documented operator contract.

#### Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

- Relates to: none



## Summary by CodeRabbit

* **New Features**
  * Interactive "plugins edit" terminal editor to manage scoped plugin configs (user/project/global) and observability components; preview and save TOML.
  * CLI now exposes a top-level plugins subcommand and shows exporter status in run/dry‑run output.

* **Documentation**
  * Docs and guides updated to use plugins.toml, with discovery/merge/validation rules and editor workflow.

* **Breaking Changes**
  * Observability/exporter settings moved to plugins.toml; legacy CLI flags, env vars, headers, and config sections removed/renamed.

* **Other**
  * Optional JSON Schema/editor metadata support for plugin/observability configs (feature-gated).



[![Review Change Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/NVIDIA/NeMo-Flow/pull/98)

Authors:
  - Will Killian (https://github.com/willkill07)
  - Ajay Thorve (https://github.com/AjayThorve)

Approvers:
  - Ajay Thorve (https://github.com/AjayThorve)
  - https://github.com/Salonijain27

URL: NVIDIA#98

Author: willkill07

ATTRIBUTIONS-Rust.md

@@ -128,6 +128,7 @@ The table below summarizes the support level for each binding surface.
 | Python | ✅ Fully Supported | Fully documented with Quick Start and Guides |
 | Node.js | ✅ Fully Supported | Fully documented with Quick Start and Guides  |
 | Rust | ✅ Fully Supported | Fully documented with Quick Start and Guides  |
+| Coding-Agent CLI | 🚧 Experimental | Install with `cargo install nemo-flow-cli`. |
 | Go | 🚧 Experimental | Source-first under `go/nemo_flow`. |
 | WebAssembly | 🚧 Experimental | Source-first under `crates/wasm`. |
 | FFI | 🚧 Experimental | Source-first under `crates/ffi`. |
@@ -161,6 +162,7 @@ The following table summarizes maintained third-party integrations and whether e
 | [LangChain](third_party/README-langchain.md), [LangGraph](third_party/README-langgraph.md), [LangChain NVIDIA](third_party/README-langchain-nvidia.md) | 🚧 Patch | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
 | [opencode](third_party/README-opencode.md) | 🚧 Patch | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
 | [OpenClaw](integrations/openclaw/README.md) | `nemo-flow-openclaw` package, `nemo-flow` plugin ID | ✅ Yes | ❌ No | ❌ No | ❌ No |
+| [Coding-Agent CLI](docs/integrate-frameworks/coding-agent-gateway.md) | `nemo-flow-cli` package for closed harnesses | ✅ Yes | ❌ No | ❌ No | ❌ No |
 | [Hermes Agent](third_party/README-hermes-agent.md) | 🚧 Patch | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
 
 Patch-based integrations offer experimental support. Our roadmap includes switching over to first-party plugins and packages where upstream extension points allow it.

Cargo.lock

@@ -23,6 +23,7 @@ axum = "0.8"
 bytes = "1"
 clap = { version = "4", features = ["derive", "env"] }
 clap_complete = "4"
+console = "0.16"
 futures-util = "0.3"
 http = "1"
 http-body-util = "0.1"

README.md

@@ -12,6 +12,7 @@ SPDX-License-Identifier: Apache-2.0
 [![npm wasm](https://img.shields.io/npm/v/nemo-flow-wasm?label=nemo-flow-wasm&color=CC3534&logo=npm)](https://www.npmjs.com/package/nemo-flow-wasm)
 [![Crates.io](https://img.shields.io/crates/v/nemo-flow?label=nemo-flow&color=B7410E&logo=rust)](https://crates.io/crates/nemo-flow)
 [![Crates.io](https://img.shields.io/crates/v/nemo-flow-adaptive?label=nemo-flow-adaptive&color=B7410E&logo=rust)](https://crates.io/crates/nemo-flow-adaptive)
+[![Crates.io](https://img.shields.io/crates/v/nemo-flow-cli?label=nemo-flow-cli&color=B7410E&logo=rust)](https://crates.io/crates/nemo-flow-cli)
 [![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/NVIDIA/NeMo-Flow)
 
 # nemo-flow-cli
@@ -50,10 +51,10 @@ with the installed `nemo-flow` command rather than link against the crate.
 
 ## Installation
 
-Install the CLI from a repository checkout:
+Install the CLI:
 
 ```bash
-cargo install --path crates/cli
+cargo install nemo-flow-cli
 ```
 
 That command installs the binary as:
@@ -103,19 +104,30 @@ Project config lives at `./.nemo-flow/config.toml`; user config lives at
 The project layer overrides system config, and the user layer overrides the
 project layer.
 
-Exporter config uses nested per-backend tables:
+Observability exporters are configured through the plugin config. Edit the user
+plugin config with:
+
+```bash
+nemo-flow plugins edit
+```
+
+The canonical plugin file is `plugins.toml`; user config lives at
+`~/.config/nemo-flow/plugins.toml` or
+`$XDG_CONFIG_HOME/nemo-flow/plugins.toml`. Project config lives at
+`.nemo-flow/plugins.toml`.
+
+Minimal ATIF example:
 
 ```toml
-[exporters.atif]
-dir = "./atif"
+version = 1
 
-[exporters.atof]
-dir = "./atof"
-mode = "append"
-filename_template = "{session_id}.jsonl"
+[[components]]
+kind = "observability"
+enabled = true
 
-[exporters.openinference]
-endpoint = "http://localhost:6006/v1/traces"
+[components.config.atif]
+enabled = true
+output_directory = "./atif"
 ```
 
 ## Documentation