v1.0.9 mobile and admin optimizations

[1.0.9] — 2026-03-06

Added

• Per-board post editing toggle — each board now has an allow_editing
  flag (off by default) that gates whether users can edit their own posts.
  When disabled the edit link is hidden and the edit endpoints return an error
  immediately, regardless of the global edit-window logic. The flag is
  exposed as a checkbox in the admin board-settings form (Enable editing).
• Per-board edit window — a companion edit_window_secs column on the
  boards table lets operators configure how long after posting a user may
  edit their own post on a per-board basis. Setting it to 0 falls back to
  the server-wide default of 300 s (5 minutes). The value is shown in the
  admin board-settings form as a number input (Edit window (s)) and is
  respected by both the edit-form handler and the edit-submit handler.
• Per-board archive toggle — a new allow_archive column on the boards
  table (default 1 on existing rows, i.e. archiving enabled) lets operators
  choose, per board, whether overflow threads are archived or permanently
  deleted when the board hits its max_threads limit. The ThreadPrune
  background worker now reads this flag from the job payload and calls either
  db::archive_old_threads or db::prune_old_threads accordingly. The
  admin board-settings form exposes this as a checkbox (Enable archive).

Fixed

• WebM AV1 → VP9 transcoding — uploaded WebM files containing an AV1
  video stream are now detected via ffprobe and re-encoded to VP9 + Opus
  by the VideoTranscode background worker. Previously, all WebM uploads
  were accepted as-is regardless of codec, meaning AV1 content would be
  served to browsers that do not support it. VP8 and VP9 WebM files are
  identified and skipped cheaply so they are never unnecessarily re-encoded.
• VP9 CRF rate-control conflict (exit status: 234) — the ffmpeg
  transcode command previously combined -b:v 0 (pure CRF mode) with
  -maxrate 2M -bufsize 4M (constrained-quality mode). libvpx-vp9 treats
  these as mutually exclusive: setting a peak bitrate cap without a target
  bitrate causes the encoder to abort with "Rate control parameters set
  without a bitrate". The -maxrate and -bufsize flags have been
  removed; the transcoder now uses pure CRF 33 with unconstrained average
  bitrate (-b:v 0), which is the correct mode for quality-driven encoding.
• E0597 borrow lifetime in db::prune_file_paths — the
  stmt.query_map(…).collect() expression at the end of a block created a
  temporary MappedRows iterator that outlived stmt (dropped at the
  closing brace), causing a compile error. The result is now collected into
  an explicit let binding before the block ends, ensuring the iterator is
  fully consumed while stmt is still in scope.

Changed

• Board model — three new fields: allow_editing: bool,
  edit_window_secs: i64, and allow_archive: bool. All DB queries that
  read or write board rows have been updated accordingly. Board backup /
  restore manifests also include these fields so settings survive a
  round-trip.