Upstream Merge

Ports changes from the official Copilot SDK (github/copilot-sdk) since last merge (06ff2ae→2186bf2).

Upstream commits analyzed (8 commits)

• Bundling support for .NET SDK (NuGet-specific, not ported)
• tool.execution_end → tool.execution_complete rename (Java SDK already used the correct name)
• CLI --no-auto-update flag added
• requestId field added to compaction complete event data
• Go/Python/Node.js SDK changes (other SDKs, not applicable)

Changes ported

Not ported (intentionally)

• Bundled CLI path resolution (GetBundledCliPath) — .NET NuGet packaging concern, not applicable to Java
• .csproj build targets for CLI download — .NET build system specific
• Client test simplifications (removing explicit cliPath) — consequence of .NET bundling
• Go/Python/Node.js SDK changes — other language SDKs

Verification

• All 172 tests pass (mvn clean test)
• Package builds successfully (mvn clean package -DskipTests)
• Code formatted with Spotless