CLI Improvements: Model Index Selection, list → ls, Unified Positional Parameter

[ng-galien]

CLI Improvements: Model Index Selection, list → ls, Unified Positional Parameter

Short Summary
Improve CLI UX: add positional <model name | index> parameter, rename list to ls, refactor model listing, and update developer guide formatting.

---

Overview

This PR streamlines and unifies how models are referenced across CLI commands. Users can now specify either a full HuggingFace-style model identifier (owner/name) or a numeric index produced by the new ls command. The previous list command has been renamed to the shorter and more conventional ls.

---

Key Changes

1. Added a required positional parameter <model name> (can be a name or an index) to model-driven commands via ModelBaseCommand.
2. Renamed the list command to ls and simplified its logic to enumerate local models with stable 1..N indices.
3. Refactored listing to avoid ad-hoc filesystem traversal and leverage shared helpers.
4. Updated multiple CLI commands to consume the new positional model argument:
   • ApiServiceCommand
   • ChatCommand
   • ClusterCoordinatorCommand
   • ClusterWorkerCommand
   • CompleteCommand
   • DownloadCommand
   • QuantizeCommand
   • RemoveCommand
   • SimpleBaseCommand
   • ModelBaseCommand
5. Updated DEVELOPER_GUIDE.md (language hint for build code block and minor formatting polish).

---

Rationale

• Faster iteration: ./run-cli.sh chat 2 instead of typing a long model identifier.
• Consistent UX across commands.
• Reduced duplication and clearer argument handling.

---

Testing

• Local build: ./mvnw -DskipTests verify completed successfully.
• Manual runtime check: ./run-cli.sh ls displays enumerated models; index-based selection works with downstream commands.

---

Example Usage

# List models with indices
./run-cli.sh ls

# Use a model by index (e.g., the second one)
./run-cli.sh chat 2

# Or by explicit identifier
./run-cli.sh chat owner/model-name

[tjake]

Great idea, just a couple issues

[ng-galien]

@tjake Thx, issues are fixed