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/media/audio-fx/audio-fx-plugin-gate/src/schemas/schemas.md

@@ -0,0 +1,61 @@
+# `schemas`
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+The `gate.schemas` module owns the Zod boundary guards for `GatePlugin` — construction options and the plugin-specific preset payload. Every public input runs through these schemas before the plugin touches any state; failures surface as `AUDIO_FX.INVALID_OPTIONS` / `AUDIO_FX.INVALID_PRESET` with the Zod issue list in `context.issues`.
+
+Keeping the schemas in a sibling folder follows the package-wide convention: hosts can import the schemas directly, run their own `safeParse` against UI input, and surface field-level errors before constructing a `GatePlugin`.
+
+## Features
+
+- `GatePluginOptionsSchema` — every field optional, ranged to match the parameter declarations in `gate.ts`: `threshold ∈ [-80, 0] dB`, `attack ∈ [0.1, 100] ms`, `hold ∈ [0, 500] ms`, `release ∈ [1, 1000] ms`.
+- `GatePresetDataSchema` — `z.object({}).strict()`. The gate has no plugin-specific state beyond its automatable parameters; the universal `parameters` map carries everything that round-trips.
+
+## Usage: Basic Example
+
+```ts
+import { GatePluginOptionsSchema } from "@suaveplan/audio-fx-plugin-gate";
+
+const parsed = GatePluginOptionsSchema.safeParse(formValues);
+if (!parsed.success) {
+    return showFieldErrors(parsed.error.issues);
+}
+const gate = new GatePlugin(parsed.data);
+```
+
+## Usage: Advanced Example
+
+```ts
+import {
+    GatePluginOptionsSchema,
+    GatePresetDataSchema,
+} from "@suaveplan/audio-fx-plugin-gate";
+
+// Validate an untrusted preset payload from a shared template
+// library before applyPreset. The plugin would catch the same issue,
+// but the host wants a friendlier error before a plugin instance is
+// constructed.
+const result = GatePresetDataSchema.safeParse(payload.data);
+if (!result.success) {
+    return reject("Gate preset is corrupt.");
+}
+```
+
+## API Reference
+
+- `GatePluginOptionsSchema` — `z.ZodObject` matching `GatePluginOptions`. All fields optional and ranged.
+- `GatePresetDataSchema` — strict empty object; rejects any unknown keys.
+
+## Implementation Notes
+
+`GatePluginOptionsSchema` uses `.finite()` on every numeric field so `NaN` and `±Infinity` are rejected at the boundary; the one-pole envelope follower's `exp(-1 / (τ · sr))` calculation would otherwise propagate non-finite coefficients into the smoothing state and contaminate every subsequent block.
+
+`attack.min(0.1)` and `release.min(1)` match the parameter declarations; values smaller than this break the one-pole smoothing assumption (the coefficient approaches `1` from below) and produce numerical artefacts in single-precision float. `hold.min(0)` allows a zero-hold gate (closes immediately when the envelope drops), which is useful for hyper-tight drum gates.
+
+`threshold.min(-80)` covers the practical noise floor of consumer audio; values below `-80 dB` are effectively "gate never closes" and don't need their own UI affordance. The upper bound at `0 dB` is the maximum useful threshold — at `0 dB` the gate is essentially always closed since real-world signals rarely exceed `0 dBFS`.
+
+The strict empty `GatePresetDataSchema` rejects any unknown keys so a stale preset format with phantom fields fails loud rather than silently dropping data.