feat(safety): report, block and hide, MODULE_API 1.21.0

USER_SAFETY.md step 2 (core), with S11-S14 decided while building it.

- Reports: POST /player/reports takes any target type, core's forum
  types or a module's registered ones. One resolver
  (model/safety/targets.js) answers "what is this item, for this
  reader" and 404s an item the reader cannot see. Every report stores
  content_reports.snapshot; the queue shows a module item from it.
- Hide for everyone: POST /admin/moderation/reports/:id/hide hides the
  item through its own moderation (forum hide as staff, or the module's
  hide) and actions the report with actioned_with = 'hide'.
- Blocks (user_blocks) name an item, never a person, and land on the
  author's account first (S12); an unlinked game identity is blocked as
  itself and becomes an account block once linked (S14). Staff cannot
  be blocked; a block on someone later promoted stops applying (S8).
- Hide for me (user_hidden_items), /auth/me/blocks and /auth/me/hidden.
- Forum reads filter blocked authors and hidden items on the server and
  carry canBlock per thread and post.
- MODULE_API 1.21.0: api.registerReportTargets,
  api.registerGameIdentities, ctx.safety.forViewer and
  ctx.safety.staffAmong, so a module filters its own per-viewer feeds on
  the server (S11) and marks lines canBlock (S13).
- Web: Hide for me / Block author in the forum menus, a Blocked section
  on both account pages, Hide for everyone in the Reports queue.
- Tests, OpenAPI, route/guard/engagement manifests regenerated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

server/src/model/teams/teamForum.db.js

@@ -79,6 +79,15 @@ async function postById(id) {
   return rows[0] || null
 }
 
+/** A thread's opening post, whatever its status — what a report on the thread quotes. */
+async function firstPostOf(threadId) {
+  const rows = await query(
+    `SELECT ${POST_COLUMNS} FROM team_forum_posts WHERE thread_id = ? ORDER BY created_at, id LIMIT 1`,
+    [threadId],
+  )
+  return rows[0] || null
+}
+
 /**
  * Append a post and move the thread's counters in the same breath.
  *
@@ -275,6 +284,7 @@ module.exports = {
   setThreadFlags,
   postsByThread,
   postById,
+  firstPostOf,
   insertPost,
   setPostStatus,
   updatePostBody,