chore: scaffold moments workspace

Cargo workspace with five crates per architecture conventions:

- moments-entities: Source enum, Event, EventQuery, SourceSummary
- moments-core:     EventReader / EventWriter ports
- moments-data:     PgStore (sqlx postgres adapter) + 0001_init.sql
- moments-api:      axum binary; /v1/{healthz,events,sources}
- moments-worker:   skeleton; pollers land in step 2

Sources committed-to for ingestion: github, gitea, hg, bugzilla.
Workstation events explicitly retired (not deferred).

Build + clippy clean. sqlx queries use the runtime API for now;
will switch to compile-time-checked macros + .sqlx offline cache
once magrathea has the moments_{ro,rw} roles and database created.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/moments-entities/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "moments-entities"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+authors.workspace = true
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+chrono.workspace = true
+thiserror.workspace = true

crates/moments-entities/src/lib.rs

@@ -0,0 +1,76 @@
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, Hash)]
+#[serde(rename_all = "lowercase")]
+pub enum Source {
+    Github,
+    Gitea,
+    Hg,
+    Bugzilla,
+}
+
+impl Source {
+    pub const ALL: &'static [Source] = &[
+        Source::Github,
+        Source::Gitea,
+        Source::Hg,
+        Source::Bugzilla,
+    ];
+
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Source::Github => "github",
+            Source::Gitea => "gitea",
+            Source::Hg => "hg",
+            Source::Bugzilla => "bugzilla",
+        }
+    }
+}
+
+impl std::str::FromStr for Source {
+    type Err = ParseSourceError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "github" => Ok(Source::Github),
+            "gitea" => Ok(Source::Gitea),
+            "hg" => Ok(Source::Hg),
+            "bugzilla" => Ok(Source::Bugzilla),
+            other => Err(ParseSourceError(other.to_string())),
+        }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("unknown source: {0}")]
+pub struct ParseSourceError(pub String);
+
+/// Raw event as stored. The presentation reshape lives in `moments-core`
+/// and runs at API request time.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Event {
+    pub id: String,
+    pub source: Source,
+    pub action: String,
+    pub occurred_at: DateTime<Utc>,
+    pub payload: serde_json::Value,
+}
+
+/// Filters accepted by `GET /v1/events`.
+#[derive(Debug, Clone, Default)]
+pub struct EventQuery {
+    pub from: Option<DateTime<Utc>>,
+    pub to: Option<DateTime<Utc>>,
+    pub sources: Option<Vec<Source>>,
+    pub limit: u32,
+}
+
+/// Per-source rollup returned by `GET /v1/sources`.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SourceSummary {
+    pub source: Source,
+    pub count: i64,
+    pub earliest: Option<DateTime<Utc>>,
+    pub latest: Option<DateTime<Utc>>,
+}