flake-register: environmental skips (platform/tool availability)

[aksOps]

Shared tracking issue for skips caused by environment, not flaky logic:

• internal/notes/history_test.go:16 — git not available
• internal/project/registry_test.go:47 — chmod semantics differ on Windows
• internal/project/registry_test.go:50 — running as root: chmod 0555 does not block writes
• internal/hookinstaller/installer_test.go:265 — symlink support requires admin on Windows

These remain legitimate environmental skips; this issue is the forever-home for them so the flake-register CI gate has a number to reference.

Owner: unassigned.

[aksOps]

Closing as intended. These four skips are legitimate environmental carve-outs, not flakes:

• internal/notes/history_test.go:16 — git binary missing on stripped-PATH machines
• internal/project/registry_test.go:47,50 — Windows chmod semantics / root UID bypasses file-mode enforcement
• internal/hookinstaller/installer_test.go:265 — Windows symlink creation requires admin

Each site retains its // TODO(#65): annotation so the flake-register CI gate keeps passing — the gate references the issue number, and closed issues are valid targets. If any new permanently-environmental skip appears, add it to the same TODO(#65): pattern; we do not need a fresh issue for each.