feat(blog): add markdown blog sourced from a gitea repo

posts are markdown files with yaml frontmatter (title, slug, date;
optional draft/public) in the grenade/blog repo. the worker's new
BlogSource polls the repo — one branch-tip request when nothing
changed — and upserts posts into events with source='blog' and
occurred_at from the frontmatter date, so imported posts keep their
original publish dates and backfill the contribution graph.

- new /v1/blog and /v1/blog/{slug} endpoints over the existing
  EventReader port; drafts stay hidden via the public gate
- new /blog and /blog/:slug routes, nav link, activity-feed entry
  with post icon and filter toggle; relative image srcs resolve to
  gitea raw urls
- shared Markdown component extracted from ProjectPage
- vite proxy target overridable via API_PROXY_TARGET for local dev

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/moments-worker/src/main.rs

@@ -4,6 +4,7 @@ use clap::Parser;
 use moments_core::{EventSource, run_poller};
 use moments_data::{
     PgStore,
+    blog::{BlogConfig, BlogSource},
     bugzilla::{BugzillaConfig, BugzillaSource},
     gitea::{GiteaConfig, GiteaSource},
     github::{GithubConfig, GithubSource},
@@ -102,6 +103,19 @@ struct Args {
     /// Seconds between bugzilla creator-query polls (defaults to 24h).
     #[arg(long, env = "BUGZILLA_POLL_INTERVAL_SECS", default_value = "86400")]
     bugzilla_interval_secs: u64,
+
+    /// Gitea repo holding blog posts (markdown + frontmatter at the repo
+    /// root, on `GITEA_HOST`). Empty string disables blog ingestion.
+    #[arg(long, env = "BLOG_REPO", default_value = "grenade/blog")]
+    blog_repo: String,
+
+    #[arg(long, env = "BLOG_BRANCH", default_value = "main")]
+    blog_branch: String,
+
+    /// Seconds between blog repo polls (cheap: one branch-tip request when
+    /// nothing changed).
+    #[arg(long, env = "BLOG_POLL_INTERVAL_SECS", default_value = "600")]
+    blog_interval_secs: u64,
 }
 
 #[tokio::main]
@@ -185,6 +199,20 @@ async fn main() -> anyhow::Result<()> {
         },
     )) as Arc<dyn EventSource>;
 
+    let blog = (!args.blog_repo.is_empty()).then(|| {
+        Arc::new(BlogSource::new(
+            http.clone(),
+            store.clone(),
+            store.clone(),
+            BlogConfig {
+                host: args.gitea_host.clone(),
+                repo: args.blog_repo.clone(),
+                branch: args.blog_branch.clone(),
+                token: args.gitea_token.clone(),
+            },
+        )) as Arc<dyn EventSource>
+    });
+
     info!(
         github_user = args.github_user,
         gitea_host = args.gitea_host,
@@ -201,6 +229,9 @@ async fn main() -> anyhow::Result<()> {
         gitea_interval_secs = args.gitea_interval_secs,
         hg_interval_secs = args.hg_interval_secs,
         bugzilla_interval_secs = args.bugzilla_interval_secs,
+        blog_repo = args.blog_repo,
+        blog_branch = args.blog_branch,
+        blog_interval_secs = args.blog_interval_secs,
         "worker started"
     );
 
@@ -210,6 +241,7 @@ async fn main() -> anyhow::Result<()> {
     let gitea_interval = Duration::from_secs(args.gitea_interval_secs);
     let hg_interval = Duration::from_secs(args.hg_interval_secs);
     let bugzilla_interval = Duration::from_secs(args.bugzilla_interval_secs);
+    let blog_interval = Duration::from_secs(args.blog_interval_secs);
 
     let github_task = tokio::spawn(async move { run_poller(github, interval).await });
     let github_search_task =
@@ -220,6 +252,8 @@ async fn main() -> anyhow::Result<()> {
     let hg_task = tokio::spawn(async move { run_poller(hg, hg_interval).await });
     let bugzilla_task =
         tokio::spawn(async move { run_poller(bugzilla, bugzilla_interval).await });
+    let blog_task =
+        blog.map(|src| tokio::spawn(async move { run_poller(src, blog_interval).await }));
 
     tokio::signal::ctrl_c().await?;
     info!("shutdown signal received");
@@ -229,6 +263,9 @@ async fn main() -> anyhow::Result<()> {
     gitea_task.abort();
     hg_task.abort();
     bugzilla_task.abort();
+    if let Some(task) = blog_task {
+        task.abort();
+    }
     Ok(())
 }