Add named Lua timers and fair event dispatch

[popduke]

Lua currently has one timer slot, and a script that repeatedly schedules a zero-delay timer can indefinitely delay readable Source input. This change supports anonymous and named one-shot timers and dispatches eligible events by their deadline or first observed Source readiness, with registration order breaking ties.

• Add optional ids to setTimeout, clearTimeout, and hasTimeout, plus event.id and event.eligibleAt. clearTimeout replaces clearTimerTask; no alias remains. The unreleased contract keeps specVersion = "1".
• Share one native-memory budget between Payload storage and timers. Each pending timer is charged an estimated 2 KiB plus three times its UTF-8 id length, without a separate timer-count limit. Delay conversion or timestamp overflow raises a catchable Lua error.
• Preserve timer ownership and Source ordering through VM initialization, replacement, failure, and shutdown. Update the Lua guide with event fields, cancellation, memory accounting, and the existing VM-wide batch completion boundary; timer ids do not provide independent reliable completion per key.

Validation on macOS arm64 with the pinned Rust 1.97.1 toolchain:

• tools/verify-rust.sh passed, including strict Clippy, generated plugins, real process lifecycle tests, Rust/Java interoperability, Loom, doctests, and rustdoc. Main-library tests: 809 passed, 6 ignored.
• Lua tests: 113 passed, 1 ignored. Flow Channel tests: 45 passed. Coverage includes zero-delay fairness, equal deadlines, id validation, overflow, cancellation, memory release, and VM handoff.
• git diff --check passed.

Linux and other architectures were not run locally. No long-running performance benchmark was performed.