Merge upstream SDK changes (2026-02-17)

[brunoborges]

Upstream Merge

Ports changes from the official Copilot SDK (github/copilot-sdk) since last merge (5016587a62652f3d184b3c6958dfc63359921aa8→5016587a62652f3d184b3c6958dfc63359921aa8).

Upstream commits analyzed (0 commits)

• No new upstream commits after .lastmerge at the time of this update.
• This PR includes Java SDK maintenance and event-port changes prepared on the sync branch.

Changes ported

Commit	Description
c18558d79	Port session mode/plan/workspace file change events; update client/request/parser wiring, tests, and docs.
168a6bfb5	Fix .github/scripts/build/format-and-test.sh repository root resolution so mvn spotless:apply and mvn clean verify run from the project root.

Not ported (intentionally)

• Additional upstream SDK feature/code changes — None available to port from upstream since .lastmerge did not advance.

Verification

• ./.github/scripts/build/format-and-test.sh passes end-to-end
• Maven verify summary: Tests run: 390, Failures: 0, Errors: 0, Skipped: 0
• Package build succeeds as part of mvn clean verify
• Spotless formatting passes