[barfle]

What this PR solves

Main CI went red after merging curated locked-console events (#10): Format, gcc build, and minimal build failed.

How it is done

• clang-format faceplate_events.c / terminal.c to satisfy Format
• Assert fchownat return in test_faceplate_events.c so gcc -Werror=unused-result passes

Upstream relationship

• Faceplate-only change, or upstream impact and contribution path explained below
• Existing kmscon attribution and per-file licence notices are preserved
• UPSTREAM.md updated if the tracked kmscon baseline changed

Display and platform impact

• No display/input/backend behaviour changes, or affected DRM/GLES/fbdev paths noted below
• Raspberry Pi and architecture implications noted
• No Dataplicity logo or restricted branding added to the core repository

Validation

• meson format --recursive --check-only or equivalent formatting check passes
• Meson build and test suite pass (CI)
• Relevant renderer/backend configuration was built
• Documentation and changelog updated for user-visible behaviour

Security and packaging

• No privilege, seat, VT, input, PTY, asset-loading, packaging, or licence impact, or impact is explained below

What to look out for

• Formatting-only + test assert; no runtime behaviour change for the events feed.

Review

• Ready for review