Bump package versions to 0.4.0 and update release notes

[RorroRojas3]

This pull request updates all four lockstep packages (Andes.Extensions.AI, Andes.Extensions.AI.Mcp, Andes.Extensions.AI.Agent, Andes.Extensions.AI.UI) to version 0.4.0. The update is solely to raise dependency minimums—there are no code, API, or behavioral changes. The packages now require newer versions of their dependencies, most notably a major upgrade to ModelContextProtocol.Core for MCP support. All packages build and test successfully with the new dependency floors.

Dependency updates:

• Andes.Extensions.AI.Mcp now requires ModelContextProtocol.Core >= 2.0.0 (was >= 1.4.1), aligning with the MCP 2026-07-28 specification and SDK release. The source required no migration and compiles without warnings. [1] [2] [3]
• Core package now floors Microsoft.Extensions.AI >= 10.8.3, and Andes.Extensions.AI.UI floors Microsoft.Extensions.AI.Abstractions >= 10.8.3 (both were >= 10.8.1). [1] [2] [3] [4]
• Andes.Extensions.AI.Agent now requires Microsoft.Agents.AI >= 1.16.0 (was >= 1.15.0). [1] [2] [3]
• Additional pin updates for ModelContextProtocol (1.4.1 → 2.0.0) and Microsoft.Extensions.AI.OpenAI (10.8.1 → 10.8.3) affect only tests and samples, not published packages. [1] [2]

Release and documentation:

• All four packages version in lockstep at 0.4.0; satellites depend on core >= 0.4.0. Release notes for 0.4.0, 0.3.1, and 0.3.0 are finalized with tags and dates. [1] [2] [3] [4] [5] [6] [7]

No .cs files changed; only dependency pins and release notes were updated.

[Copilot]

Pull request overview

This PR bumps the lockstep package versions to 0.4.0 and raises dependency minimums (notably updating MCP dependencies to the ModelContextProtocol 2.0.0 line), while also finalizing and adding release notes for 0.4.0/0.3.1/0.3.0.

Changes:

• Update central package pins in Directory.Packages.props (including ModelContextProtocol(.Core) → 2.0.0 and Microsoft.Extensions.AI* → 10.8.3).
• Bump all four shipping packages’ <Version> to 0.4.0.
• Add/finalize release notes for v0.4.0, and set tags/dates for v0.3.1 and v0.3.0.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Directory.Packages.props	Raises centrally-managed dependency versions (including MCP 2.0.0 and Microsoft.Extensions.AI 10.8.3).
Andes.Extensions.AI/Andes.Extensions.AI.csproj	Bumps package version to 0.4.0.
Andes.Extensions.AI.Mcp/Andes.Extensions.AI.Mcp.csproj	Bumps package version to 0.4.0.
Andes.Extensions.AI.Agent/Andes.Extensions.AI.Agent.csproj	Bumps package version to 0.4.0.
Andes.Extensions.AI.UI/Andes.Extensions.AI.UI.csproj	Bumps package version to 0.4.0.
releases/v0.4.0.md	Adds 0.4.0 release notes documenting the dependency floor changes and verification.
releases/v0.3.1.md	Finalizes 0.3.1 release notes header with tag/date.
releases/v0.3.0.md	Finalizes 0.3.0 release notes header with tag/date.

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