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/api-stack/api/api-ws/src/reconnect-token/reconnect-token.md

@@ -0,0 +1,86 @@
+# `reconnect-token` — HMAC envelope for resumable WebSocket sessions
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+When the host closes a WebSocket connection cleanly (heartbeat failure,
+deploy, transient network issue), it issues a reconnect token the client can
+present on a follow-up upgrade request. The host validates the HMAC and
+re-attaches the previous subscription set with no plugin code change. This
+module owns the abstract payload shape and a Web-Crypto-based sign/verify
+pair. State is carried inside the token; the host stores nothing.
+
+The TTL default is 5 minutes, matching design doc §11.5. Anything older is
+rejected with `WS.RECONNECT_TOKEN_INVALID` so a stolen token has a hard
+upper bound on its usefulness.
+
+## Features
+
+- Strict Zod schema for the payload — `tenant`, `principalId`,
+  `lastEventId` (nullable), `exp`.
+- `signReconnectToken(input, { secret, clock?, ttlMs? })`.
+- `verifyReconnectToken(token, { secret, clock? })` — throws on bad
+  encoding, bad MAC, bad shape, or expired payload.
+- Uses Web Crypto (`globalThis.crypto.subtle`) — runs unchanged in Bun,
+  Node 20+, browser, and worker tiers.
+- Constant-time MAC comparison.
+
+## Usage: Basic
+
+```ts
+import {
+    signReconnectToken,
+    verifyReconnectToken,
+} from "@suaveplan/api-ws/reconnect-token";
+
+const secret = crypto.getRandomValues(new Uint8Array(32));
+const token = await signReconnectToken(
+    { tenant: "t1", principalId: "p1", lastEventId: "e-9" },
+    { secret }
+);
+const payload = await verifyReconnectToken(token, { secret });
+```
+
+## Usage: Advanced
+
+```ts
+import {
+    RECONNECT_TOKEN_TTL_MS,
+    signReconnectToken,
+    verifyReconnectToken,
+} from "@suaveplan/api-ws/reconnect-token";
+
+const clock = (): number => mockNow;
+let mockNow = 1_000_000;
+
+const token = await signReconnectToken(
+    { tenant: "t1", principalId: "p1", lastEventId: null },
+    { secret, clock, ttlMs: RECONNECT_TOKEN_TTL_MS }
+);
+mockNow += RECONNECT_TOKEN_TTL_MS;
+await verifyReconnectToken(token, { secret, clock }); // throws WS.RECONNECT_TOKEN_INVALID
+```
+
+## API Reference
+
+- `const RECONNECT_TOKEN_TTL_MS = 300_000`.
+- `interface ReconnectTokenPayload { tenant, principalId, lastEventId, exp }`.
+- `reconnectTokenPayloadSchema: z.ZodSchema<ReconnectTokenPayload>`.
+- `signReconnectToken(input, options): Promise<string>`.
+- `verifyReconnectToken(token, options): Promise<ReconnectTokenPayload>` —
+  throws `WsError(WS.RECONNECT_TOKEN_INVALID)` on every failure mode.
+
+## Implementation Notes
+
+- HMAC-SHA-256 over the canonical JSON of the payload (the exact bytes
+  signed are the bytes verified — no re-serialisation).
+- `base64url` encoding (no padding, `-`/`_` instead of `+`/`/`) keeps the
+  token URL-safe for the `?reconnectToken=…` query parameter.
+- The verifier uses constant-time comparison so a malicious client cannot
+  recover the MAC byte-by-byte through timing.
+- All four failure modes (malformed wire form, bad encoding, bad MAC,
+  expired) collapse to a single `WS.RECONNECT_TOKEN_INVALID` code so
+  clients cannot probe for which guard rejected them.