feat: add adaptive plugin editor support

[willkill07]

Overview

Stacked PR on top of NVIDIA/NeMo-Flow#128 (wkk_enable-adaptive-plugin). This PR targets wkk_enable-adaptive-plugin and should be reviewed after or alongside NVIDIA#128.

Adds nemo-flow plugins edit support for Adaptive plugin configuration options without exposing the default adaptive schema version as an operator-edited field.

• I confirm this contribution is my own work, or I have the right to submit it under this project's license.
• I searched existing issues and open pull requests, and this does not duplicate existing work. This is intentionally stacked on NVIDIA/NeMo-Flow#128.

Details

• Add editor metadata for Adaptive config sections: agent_id, state.backend, telemetry, adaptive_hints, tool_parallelism, acg, acg.stability_thresholds, and policy.
• Extend the CLI plugin editor to show Observability and Adaptive components in one plugins.toml editor flow.
• Add recursive nested-section editing, float field prompts for ACG thresholds, and cursor-position memory when navigating back from selected entries.
• Keep default adaptive version = 1 out of editor-created and editor-saved adaptive config.
• Update tests and docs for the expanded editor behavior.

Validation run:

• cargo fmt --all
• cargo test -p nemo-flow-cli plugins::tests
• cargo test -p nemo-flow-adaptive test_adaptive_editor_schema_covers_canonical_options
• cargo clippy -p nemo-flow-cli --all-targets -- -D warnings
• git diff --check
• Commit-time pre-commit hooks, including Cargo clippy/check and docs markdown linkcheck

Where should the reviewer start?

Start with crates/cli/src/plugins.rs for the stacked editor flow. Then review crates/adaptive/src/config.rs for the Adaptive editor metadata. This PR is stacked against NVIDIA/NeMo-Flow#128; compare against wkk_enable-adaptive-plugin for the focused diff.

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

• Closes NMF-151

[willkill07]

Closing in favor of opening this stacked PR on NVIDIA/NeMo-Flow.