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/coordinator.md

@@ -191,7 +191,7 @@ also include:
 Example prompt template:
 
 ```
-You are an implementation specialist for the @alkdev/alknet project.
+You are an implementation specialist for the @alkdev/alkblobs project.
 
 Your task: {{task}}
 
@@ -204,11 +204,10 @@ Your task: {{task}}
 7. Push: git push origin $(git branch --show-current)
 8. Notify: worktree({action: "notify", args: {message: "Task completed: {{task}}. <brief summary>", level: "info"}})
 
-Key project constraints (@alkdev/alknet):
+Key project constraints (@alkdev/alkblobs):
 - Rust: use cargo build, cargo clippy, cargo fmt, cargo test
 - No comments in code
-- anyhow::Result for application errors, thiserror for library error types
-- Feature flags for transports (tls, iroh, acme)
+- thiserror for error types
 - Async via tokio runtime
 - No panics in library code
 ```