feat: social graph features

migrations/0024_create_post_reports.up.sql

@@ -0,0 +1,19 @@
+-- Post reports — a viewer flags a specific post (not its author) with a
+-- category + optional free-text reason. Mirrors user_reports but keyed to
+-- a post; resolved_at is one-way (admins clear it later). The partial
+-- index keeps the open-reports queue cheap to list.
+CREATE TABLE IF NOT EXISTS post_reports (
+    id           UUID         PRIMARY KEY DEFAULT gen_random_uuid(),
+    reporter_id  UUID         NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    post_id      UUID         NOT NULL REFERENCES posts(id) ON DELETE CASCADE,
+    category     VARCHAR(32)  NOT NULL,
+    reason       TEXT         NOT NULL DEFAULT '',
+    created_at   TIMESTAMPTZ  NOT NULL DEFAULT now(),
+    resolved_at  TIMESTAMPTZ
+);
+
+CREATE INDEX IF NOT EXISTS post_reports_post_idx
+    ON post_reports (post_id, created_at DESC);
+
+CREATE INDEX IF NOT EXISTS post_reports_unresolved_idx
+    ON post_reports (created_at DESC) WHERE resolved_at IS NULL;