[proggeramlug]

Summary

api-docs-drift currently fails for every open PR — including ones whose only change is unrelated runtime code (e.g. #3733). Root cause: the constants manifest entries for OS-specific values are #[cfg(target_os = ...)]-gated, so the compiled manifest differs by build OS, and the generated docs (docs/api/perry.d.ts, docs/src/api/reference.md) differ depending on which platform ran the generator.

CI regenerates on Linux and fails on any diff. The moment the committed docs are regenerated on macOS (a maintainer's machine), the OS-specific constants flip:

Gated to Linux	Gated to macOS
O_DIRECT, O_NOATIME, SIGSTKFLT, SIGPOLL, SIGPWR, RTLD_DEEPBIND	O_SYMLINK, SIGINFO

…and api-docs-drift then fails for all subsequent PRs until the docs are regenerated on Linux again. (Diagnosed while trying to land #3733: its only change is object_ops.rs, yet CI showed a constants-module doc diff adding the Linux constants and removing the macOS ones.)

Fix

List all eight platform-specific constants unconditionally in the manifest, so the manifest — and the generated docs — are byte-identical on every host. This documents the cross-platform superset (the convention Node's own @types follow). The runtime constants module still only exposes a real value where the OS provides one, so behavior is unchanged: an absent constant reads as undefined, matching Node.

Verification

• Docs regenerated on macOS now contain both the Linux and macOS constants (the deterministic union), so a Linux CI regen produces the identical output → no drift. This PR's own api-docs-drift should pass, and it unblocks the check for all PRs going forward.
• The manifest test that asserted the old gating (RTLD_DEEPBIND.is_some() == cfg!(linux-gnu)) is updated to assert unconditional presence; all 25 perry-api-manifest tests pass. cargo fmt --check clean.

Impact

Unblocks the api-docs-drift required check repo-wide. After this merges, the #3527 chain PRs (#3733 and the regex fix #3777) rebase green.