feat: initial repo setup (Phase 0 scaffolding)

- AGENTS.md: repo conventions adapted from alkcall/alksocks (store
  posture, multi-hash requirement, no-iroh-wire rule; no fuzz gate yet)
- Cargo.toml + src/lib.rs: bare lean lib skeleton (tokio async, thiserror)
- docs/research/phase-0.md: Phase 0 draft — vision, prior art (iroh-blobs
  store, gix-odb, alknet appfile probe, alkcall), OQ register, POC plan
- .gitignore, LICENSE-APACHE/MIT
- Re-pointed stale alknet/alkcall references in .opencode/agents/ and
  docs/sdd_process.md

Verification: cargo build/test, cargo clippy --all-targets -- -D
warnings, cargo fmt --check, cargo doc --no-deps — all pass

.opencode/agents/architect.md

@@ -326,10 +326,10 @@ result, a concrete use case to arrive.
 
 A decision should be `deferred(scope)` when:
 
-- The use case isn't concrete (e.g., "we don't know what the agent crate
-  will need from the call protocol")
+- The use case isn't concrete (e.g., "we don't know what the consumer
+  crate will need from the blob API")
 - The options depend on something that doesn't exist yet (e.g.,
-  "depends on the alknet-http crate spec")
+  "depends on the alkgit crate spec")
 - The trade-off requires data that can only come from implementation
   (e.g., "need performance benchmarks to choose between X and Y")
 - The decision is genuinely not needed for the current scope (e.g., "the
@@ -373,10 +373,10 @@ A decision should be `deferred(unclear)` when:
    (implies it's decided).
 2. **State the blocking condition** (`deferred(scope)`) or
    **investigation target** (`deferred(unclear)`) — what specific thing
-   would unblock this? Be concrete: "blocked on: alknet-agent crate spec
-   exists" or "investigation: work through 2+ example outbound-dial use
-   cases (hub→worker, worker→hub) to see how verifier-selection +
-   provider + connector compose."
+   would unblock this? Be concrete: "blocked on: alkgit crate spec
+   exists" or "investigation: work through 2+ example store use
+   cases (small-blob kv backend, large-blob fs fallback) to see
+   how backends + hashes + ACL compose."
 3. **State the impacts** — what does this block downstream? Be
    specific: "blocks the first hub deployment because the hub dials
    workers" not "blocks the hub crate." This is the triage signal that