Add storage stack modules and track them in git

The modules workspace previously ignored every path matching `storage-*`,
which kept all Hypercore, Hyperbee, Hyperdrive, and Autobase packages out
of version control. Narrow .gitignore to test-artifact patterns only so
production category trees are committed.

Storage packages (23 total):
- storage-hypercore (7): replicator, seed-policy, fork-picker, merkle-sync,
  priority-fetch, bitfield-scheduler, audit-chain
- storage-hyperbee (5): batch-write, diff-follow, range-watch,
  secondary-index, tombstone-gc
- storage-hyperdrive (6): entry-catalog, gc-sweep, mirror-sync, mount-bridge,
  version-snapshot, watch-notify
- storage-autobase (5): fork-choice, view-sync, writer-lease, indexer-bus,
  light-writer

Implementation highlights:
- Shared attach/gossip helpers in _shared/storage-gossip-base.js
- P2P modules use Protomux gossip via p2p-bare; local planners omit swarm
- Recent deepen pass: priority queues, batch caps, audit export/import,
  watch/notify aliases on range-watch, fork/view lease helpers, etc.
- Per-package README, docs/api.md, docs/architecture.md, tests, examples

Also update modules/README.md doc hub links for the full storage stack
(hypercore, hyperbee, hyperdrive, autobase).

Co-authored-by: Cursor <[email protected]>

storage-hyperdrive/hyper-p2p-drive-watch-notify/docs/api.md

@@ -0,0 +1,110 @@
+# API: hyper-p2p-drive-watch-notify
+
+**Protocol:** `drive-watch-notify/v1`
+
+**Export:** `HyperP2PDriveWatchNotify`
+
+## Overview
+
+Path watchers with local callbacks plus gossip `drive-change` notifications; bridge to `hyper-p2p-distributed-event-bus` for app-wide fanout.
+
+## Constructor
+
+```js
+const mod = new HyperP2PDriveWatchNotify(opts)
+```
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `topic` | string \| Buffer \| null | null | Hyperswarm topic; gossip attaches when set |
+| `keyPair` | Ed25519 KeyPair | random | Signing identity for swarm |
+| `drive` | object \| null | null | Attached drive instance (`attach()` also supported) |
+
+## Methods
+
+### `attach(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `watchPath(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:**
+  - `Error: callback required`
+
+### `notifyChange(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `unwatch(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `getStats(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `ready(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `close(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+## Events
+
+| Event | Payload |
+|-------|---------|
+| `change` | `{ key, value, op, delivered }` |
+| `closed` | no payload |
+
+## getStats()
+
+Returns `{ ...this._stats, protocol }` plus module-specific counters (pending queues, registry sizes, gossip in/out when P2P).
+Local modules report hot-path counters only; P2P modules include gossip traffic when `topic` is set.
+
+## Errors
+
+Stable message substrings: see [`../../_shared/ERROR_CODES.md`](../../_shared/ERROR_CODES.md).
+
+Validation helpers may throw `ValidationError` (e.g. `peer is required`, `path is required`).
+
+### Documented `throw new Error(...)` strings
+
+- `callback required`
+
+## P2P
+
+When `topic` is set, `ready()` joins Hyperswarm and opens gossip for `drive-watch-notify/v1`.
+Outbound payloads use `sendGossip` (Protomux peer map); inbound handled in `_onGossip`.
+
+### Gossip message types
+
+- `drive-change`
+
+## Testing
+
+```bash
+npm install && npm test
+```
+
+## Common flows
+
+1. `watchPath(path, cb)` — prefix-aware callbacks.
+2. `notifyChange(path, op)` — local delivery + gossip `drive-change`.
+3. Remote gossip replays into matching watches with `remote: true`.
+

storage-hyperdrive/hyper-p2p-drive-watch-notify/docs/architecture.md

@@ -0,0 +1,44 @@
+# Architecture: hyper-p2p-drive-watch-notify
+
+**Category:** Storage (Hyperdrive)
+
+```mermaid
+flowchart LR
+  App[Application] --> Mod[HyperP2PDriveWatchNotify]
+  Mod --> Gossip[Hyperswarm gossip]
+  Gossip --> Peer[Remote peers]
+```
+
+## Sequence (P2P)
+
+```mermaid
+sequenceDiagram
+  participant App
+  participant Mod as Module
+  participant SW as Hyperswarm
+  participant Peer
+  App->>Mod: ready(topic)
+  Mod->>SW: join(topic)
+  SW->>Peer: connection
+  Mod->>Peer: gossip payload
+  Peer-->>Mod: onmessage
+  Mod-->>App: emit(event)
+```
+
+## Wire messages
+
+| type | fields | direction | behavior |
+|------|--------|-----------|----------|
+| `drive-change` | path, op, at | gossip | fanout path change |
+
+## State model
+
+- In-memory `Map` / `Set` / array structures for hot path
+- Optional attached HyperDrive via `attach()`
+- `close()` clears ephemeral state and destroys swarm when P2P
+
+## Composition
+
+Composes with: `hyper-p2p-distributed-event-bus`.
+
+Storage gossip helpers: [`../../_shared/storage-gossip-base.js`](../../_shared/storage-gossip-base.js).