Restore the topology command and fix stale "soon" badges on the site #179

Why

PR #174 (store support) was rebased from a branch that predated two pieces of
already-shipped work: the topology subcommand's dispatch wiring in
cmd/specsync/main.go, and the "See who's already working what" feature card
on specsync.se. The flat-diff reapplication silently dropped the topology
case from knownSubcommands and the main() switch, so specsync topology
now fails with "unknown subcommand" even though runTopology and all its
tests are still present and working.

Separately, while reviewing the site after that merge: three feature cards
(design notes overflow #139, topology #168, adopt #160) still carry a "soon"
badge even though all three shipped weeks ago.

What Changes

• Restore "topology": true in knownSubcommands, the case "topology": runTopology(rest) dispatch arm, and topology in the subcommand list
  printed on an unknown-subcommand error.
• Drop the stale "status": "soon" / "issue" fields from the three
  already-shipped feature cards in site/features.json.

Impact

• Affected code: cmd/specsync/main.go, site/features.json
• No spec delta: restores previously-specified, previously-tested behavior
  that regressed in a merge; doesn't change any contract.