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-hyperbee/hyper-p2p-bee-tombstone-gc/docs/api.md

@@ -0,0 +1,120 @@
+# API: hyper-p2p-bee-tombstone-gc
+
+**Protocol:** `bee-tombstone-gc/v1`
+
+**Export:** `HyperP2PBeeTombstoneGc`
+
+## Overview
+
+Soft-delete tombstones with time-based `gcSweep`; pair with `hyper-p2p-temporal-index` when retention policies are time-ordered.
+
+## Constructor
+
+```js
+const mod = new HyperP2PBeeTombstoneGc(opts)
+```
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `bee` | object \| null | null | Attached bee instance (`attach()` also supported) |
+
+## Methods
+
+### `attach(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `tombstone(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:**
+  - `Error: key required`
+
+### `gcSweep(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:**
+  - `Error: olderThanMs must be non-negative`
+
+### `listTombstones(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `restore(…)`
+
+- **Returns:** module-specific (see implementation)
+
+- **Throws:** — (none in method body)
+
+### `pendingTombstones(…)`
+
+- **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 |
+|-------|---------|
+| `tombstone` | `{ key }` |
+| `sweep` | `{ removed }` |
+| `restore` | `{ key }` |
+| `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
+
+- `key required`
+- `olderThanMs must be non-negative`
+
+## P2P
+
+Library-only: no swarm join. `ready()` resolves immediately.
+`getStats().protocol` still reports the module protocol id for logging.
+
+## Testing
+
+```bash
+npm install && npm test
+```
+
+## Common flows
+
+1. `tombstone(key, meta)` — mark pending delete.
+2. `gcSweep(olderThanMs)` — purge expired tombstones.
+3. `restore(key)` — cancel tombstone before sweep.
+

storage-hyperbee/hyper-p2p-bee-tombstone-gc/docs/architecture.md

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+# Architecture: hyper-p2p-bee-tombstone-gc
+
+**Protocol:** `bee-tombstone-gc/v1` · **P2P:** no
+
+## Role
+
+Soft-delete registry: mark keys tombstoned, sweep after `olderThanMs`, optional `restore`.
+
+## State
+
+`Map<key, { at, meta }>`
+
+## Methods
+
+| Method | Effect |
+|--------|--------|
+| `tombstone(key, meta?)` | Mark deleted |
+| `isTombstoned(key)` | Query |
+| `gcSweep(olderThanMs)` | Remove stale entries |
+| `listTombstones` / `restore` | Admin |
+
+## Events
+
+`tombstone`, `sweep`, `restore`, `closed`
+
+Run physical `bee.del` in your app after sweep returns keys.