feat: add db and multi-archive web UI foundation (#8)

* Add SQLite metadata database support

* Implement archive metadata database

* chore: let's guess cargoHash because there's something wrong with nixpkgs!

* Gate test-only database helpers behind cfg(test)

* Fix archive database row identity

* Use serde for archive metadata JSON

* Finalize archive runs at command level

* Handle archive command errors without panics

* Cover tweet entry metadata recording

* Document static regex invariants

* docs: add web UI design spec

* docs: add web UI implementation plan

* chore: move cli into workspace crate

* chore: track workspace crates directory

* refactor: extract archive core crate

* refactor: add core archive opening APIs

* refactor: rename taxonomy model to tags

* feat: add archive query APIs

* feat: add web server registry

* feat: expose archive server APIs

* feat: add archive table web UI

* fix: complete web UI smoke path

* docs: add architecture mental model

* docs: remove private superpowers plans

* nix: split cli and server packages

* chore: remove PLAN.md

crates/archivr-core/src/lib.rs

@@ -0,0 +1,5 @@
+pub mod archive;
+pub mod database;
+pub mod downloader;
+pub mod hash;
+pub mod twitter;