Move docs/ package mirror into document-navigator plugin

Relocate the ~6k-file docs tree from the repo root into
plugins/document-navigator/docs/ so the plugin is self-contained and
portable. docs/superpowers/ (specs and plans) stays at the repo root.

Moved via cp+rm rather than git mv because directory rename() fails with
EPERM on this WSL /mnt DrvFs mount; git rename-detection pairs the
identical-content files at commit time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/docs/foundation/timing/README.md

@@ -0,0 +1,15 @@
+# `timing`
+
+Cron, stopwatches, throttling, debouncing, and scheduling.
+
+<!-- begin:auto-docs -->
+## Packages in `timing`
+
+3 packages.
+
+| Package | Description |
+|---|---|
+| [`@suaveplan/cron`](./cron/README.md) | Universal cron expression parser, next-fire calculator with timezone + DST awareness, and an opt-in lightweight in-process scheduler. Zero external cron depend… |
+| [`@suaveplan/datetime`](./datetime/README.md) | Timezone-aware date/time utilities covering the most common application-layer date operations that the native `Date` API leaves unaddressed. The package provid… |
+| [`@suaveplan/timing`](./timing/README.md) | Timing and scheduling utilities for application-layer time management. The package covers measurement (stopwatch with lap recording), rate control (throttle an… |
+<!-- end:auto-docs -->