greenfield: clean slate for ALPN-as-service pivot

Delete old source crates (alknet-core, alknet, alknet-napi), old
architecture docs (ADRs, specs, open questions), old research docs
(phase2, event-sourcing, feasibility, etc.), old tasks, and obsolete
reference material (gitserver/MPL, honker, nats, rustfs, polyglot,
keystone, distributed-identity).

Keep: alknet-secret (standalone, compiles), pivot docs, iroh and ssh
references, rudolfs reference (MIT/Apache, fork candidate), ops docs,
sdd_process.md, and licenses.

Previous implementation preserved at /workspace/@alkdev/alknet-main/
for reference during porting.

Workspace compiles: cargo check + 14 tests pass for alknet-secret.

Cargo.toml

@@ -1,8 +1,5 @@
 [workspace]
 members = [
-    "crates/alknet-core",
-    "crates/alknet",
-    "crates/alknet-napi",
     "crates/alknet-secret",
 ]
 resolver = "2"