Scaffold tier 2 and 3, the schema, the website, and self-hosted-first

Store: the full Postgres schema as an embedded migration. UUIDv7 keys so
`ORDER BY id` is a free chronological index; raw MIME and attachments live
in object storage with only a key in the row; `pods` present from day one
because retrofitting tenancy costs more than an unused column. API keys are
stored as a SHA-256 hash — a database dump must not be a set of live
credentials.

API: the v0 route table, including `ingest`, which closes the
receive→thread→extract loop with zero mail infrastructure and is what makes
the agent layer testable in CI. Scopes are a closed enum rather than
strings, so "can send mail" and "can mint keys" are not one typo apart.
Internal errors are logged in full and reported as a bare string.

MCP: the tool catalogue, six tools. Adding a row here is the only way an
agent gains a capability — a new REST route is invisible until someone opts
it in. Three tests guard the rule that no tool can ever reach key
management; CI fails rather than production.

ADR 0006: enterprise self-hosted first. A hosted offering comes only after
we have run this ourselves long enough to have a deliverability record
worth selling. `pods` stays in the schema as the thing that keeps that path
open — do not remove it as dead code.

Also: multi-stage Dockerfile running as a non-root system user with no
shell in the runtime image, and the openmail.karti.ai static page.

17 tests, zero clippy warnings, fmt clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JkyvfNJGTshJNE9FtwPLk7

crates/openmail-api/src/lib.rs

@@ -1,31 +1,21 @@
 //! The v0 REST API.
 //!
-//! Bearer auth, agent-shaped resources. Paths are kept close to the shape
-//! existing agent-mail tooling expects, so a client can be pointed at a
-//! self-hosted `OpenMail` with a base-URL swap. Where compatibility and a clean
-//! native shape conflict, the native shape wins and the difference is
-//! documented.
-//!
-//! ```text
-//! POST   /v0/inboxes
-//! GET    /v0/inboxes                       list
-//! GET    /v0/inboxes/{id}
-//! POST   /v0/inboxes/{id}/messages/send
-//! GET    /v0/inboxes/{id}/messages         limit, page_token, labels
-//! GET    /v0/inboxes/{id}/messages/{mid}
-//! POST   /v0/inboxes/{id}/messages/{mid}/reply
-//! GET    /v0/inboxes/{id}/threads
-//! GET    /v0/inboxes/{id}/threads/{tid}
-//! ```
+//! Bearer auth, agent-shaped resources. Paths stay close to the shape existing
+//! agent-mail tooling expects, so a client can target a self-hosted `OpenMail`
+//! with a base-URL swap. Where compatibility and a clean native shape conflict,
+//! the native shape wins and the difference is documented.
 
-#[derive(Debug, thiserror::Error)]
-pub enum Error {
-    #[error("unauthorized")]
-    Unauthorized,
-    #[error("not found")]
-    NotFound,
-    #[error("bad request: {0}")]
-    BadRequest(String),
-    #[error(transparent)]
-    Store(#[from] openmail_store::Error),
+pub mod auth;
+pub mod error;
+pub mod routes;
+
+pub use error::Error;
+
+use sqlx::PgPool;
+
+/// Everything a handler may reach. Deliberately small — a handler that needs
+/// something not in here is usually a handler doing too much.
+#[derive(Clone)]
+pub struct AppState {
+    pub db: PgPool,
 }