Event-sourced applicant/subscriber/project aggregates, generalized resources

Replaces the free-string, direct-KV-mutate state model in answers.rs
with a proper event log (events/store.rs, JetStream-backed, CAS via
expected_last_subject_sequence) and three pure state machines
(aggregates/{applicant,subscriber,project}.rs). Closes a real
lost-update race in the old transition_answer (concurrent decisions on
the same item could both win, publishing contradictory events). KV
buckets become best-effort read-model projections, not the source of
truth. Content-declared transition targets are now validated at
load/reload time against the real compiled transition tables, not
accepted as arbitrary strings.

Buckets renamed to describe their content, not their relation to the
app (portal_applicants -> applicants, etc); "inquiry" folded into a
richer "project" concept.

ResourceSpec generalized beyond a single KV bucket: Kv | GiteaStarred |
GiteaOrgRepos | Url sources, with an optional jq filter (via the jaq
crate) to shape live data for the frontend. Url source is SSRF-guarded
(https-only, rejects loopback/private/link-local, real DNS resolve).

New headless question_lint binary (validates content against compiled
transition tables with no NATS/OIDC/server involved) and a one-time
backfill_events binary (dry-run by default) for migrating existing KV
data onto the new event log.

Questions get an optional `responsible` contact plus a lightweight
"report this question" action.

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

src/main.rs

@@ -30,6 +30,7 @@ async fn main() -> anyhow::Result<()> {
     let content_branch = std::env::var("CONTENT_BRANCH").unwrap_or_else(|_| "main".to_string());
     let gitea_base = content::gitea_api_base(&content_repo)?;
     let questions = content::load_questions_from_gitea(&content_repo, &content_branch, "questions").await?;
+    content::validate_questions(&questions)?;
     tracing::info!(count = questions.len(), repo = %content_repo, branch = %content_branch, "loaded content");
     let questions = Arc::new(arc_swap::ArcSwap::from_pointee(questions));
 
@@ -50,6 +51,7 @@ async fn main() -> anyhow::Result<()> {
     // names whatever bucket an alternative's `record_as` should write
     // into, and `answers::store_answer` creates it on first use.
     let jetstream = async_nats::jetstream::new(nats.clone());
+    portal::events::store::ensure_stream(&jetstream).await?;
 
     let oidc_state = Arc::new(oidc::Oidc::from_env().await?);