Migrate to iroh 1.0 and iroh-blobs 0.103

The 0.35 pin's rationale ("the post-0.35 rewrite is not yet production
quality") expired when iroh hit 1.0 in June 2026: the rewrite line
(0.103) is now the production line and the only one receiving fixes.

The rewrite replaced wrappable store traits with an irpc-based API, so
the seams moved:

- shaped.rs: the 440-line ShapedStore trait wrapper becomes a provider
  event handler. Trust gating (untrusted peers see only openly-served
  hashes) now intercepts requests before any bytes move; upload rate
  limiting rides the provider's Throttle hook; upload progress events
  come from per-request update streams. The TokenBucket is unchanged.
- store.rs: FsStore's API handle replaces the store traits, and the
  LocalPool machinery for non-Send futures is gone. GC is now the
  store's built-in periodic mark-and-sweep, fed by a pin-roots snapshot
  via the protect callback (new config knob gc_interval_secs, default
  300); the on-demand Gc request answers Unimplemented, and the gc
  conformance test polls the sweep instead.
- transfer.rs: BlobsProtocol + Router replace handle_connection, the
  new multi-provider Downloader replaces the old queue, and mdns
  discovery moved to the iroh-mdns-address-lookup crate (it left iroh
  core in 1.0). Ticket-embedded provider addresses feed a MemoryLookup
  address book. Endpoint presets: Minimal (LAN-only default) or N0
  (wan_upload), preserving the old relay posture.
- Node* became Endpoint* throughout; announcement signatures use iroh's
  own Signature type (ed25519-dalek dep dropped); iroh-io dropped.

Known regression: max_download_bytes_per_sec is currently not enforced
— download shaping rode the old store's batch writer and 0.103's
downloader has no equivalent seam yet.

Announcement wire format note: EndpointAddr serializes differently than
NodeAddr, so pre- and post-migration daemons won't parse each other's
LAN announcements. Announcements are live-only, nothing stored breaks.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

SPECS.md

@@ -27,8 +27,8 @@ varde/
 ```
 
 **Key dependencies and versions:**
-- `iroh-blobs = "0.35"` — pin this. Per upstream, the post-0.35 rewrite is not yet production quality; 0.35 is the recommended production line. Use its persistent fs store (`iroh_blobs::store::fs`).
-- `iroh` — matching version compatible with iroh-blobs 0.35.
+- `iroh-blobs = "0.103"` — the post-rewrite line, now the production line (the old 0.35 pin predated iroh 1.0). Use its persistent fs store (`iroh_blobs::store::fs`).
+- `iroh = "1"` — iroh 1.0, stable protocol and API.
 - `tokio`, `serde`, `serde_json`, `tracing`, `clap` (ctl only), `anyhow`/`thiserror`.
 - `zbus` for NetworkManager metered-status (feature-gated, `default-features` on Linux only).