Update README with installation, configuration, and GUI links

[shenhao-stu]

This pull request updates the documentation to reflect new features, improvements in installation and configuration, and enhanced user guidance. The most important changes include updates to the roadmap for new modes and frontends, a streamlined installation process, revised LLM configuration examples, and improved frontend selection instructions.

Roadmap and Feature Updates:

• Added entries to the roadmap in both English and Chinese for new features: TUI v3 frontend (frontends/tui_v3.py), Morphling mode (memory/morphling_sop.md), Goal Hive mode (memory/goal_hive_sop.md), and Goal mode (reflect/goal_mode.py). These highlight major recent and upcoming functionalities. [1] [2]
• Expanded the list of community projects to include FroStorM/A3Agent. [1] [2]

Installation and Setup Improvements:

• Overhauled the installation instructions in docs/GETTING_STARTED.md to prioritize a new one-click install script for Windows, Linux, and macOS, while still providing manual and ZIP-based alternatives.

LLM Configuration and Usage:

• Updated configuration examples to recommend the Native Claude protocol as the default, clarified variable naming conventions for session types, and documented advanced mixin failover usage. Also, deprecated older session types and referenced comprehensive field documentation.

Frontend Launch and Usage:

• Replaced the old GUI launch instructions with a table summarizing all available frontends (desktop, TUI v2/v3, Streamlit), their launch commands, and usage notes, improving clarity for new users.

Feature Discovery Table:

• Added new rows to the "Agent can help you with..." table for recently added modes: Goal, Goal Hive, Conductor, and Morphling, making it easier for users to discover and activate these features.