Add Opinion Wars: week-long two-faction battles attached to posts

A new post attachment type beside polls: the composer gains a Start
Opinion War builder (same disabled-inputs opt-in as the poll builder)
that names exactly two factions; the battle runs for exactly 7 days
from post creation. Members join a side, may defect at any time
(damage already dealt stays with the faction it was dealt to), and
fight once per 24 hours per battle. A fight spends 25 Code Farm coins
and deals deterministic level-weighted damage: 100 + 10 * min(level,
20) HP, so a newcomer deals 110 and a veteran caps at 300 - no
randomness anywhere.

The battle renders on the post card as a CSS pixel-art battlefield
(box-shadow sprites: castles, faction flags, marching soldiers, a
flickering campfire; steps() animation, disabled under reduced motion)
with live HP bars, a countdown, the viewer's faction strip, top
contributors and an event ticker. Live frames ride pub/sub on
public.battle.{uid} via a relay on the service-lock owner, with the
durable opinion_war_events trail (per-war atomic seq) as the source of
truth and a 15s incremental poller as fallback. /battles lists battles
with active/ended/mine filters, search and pagination.

Every mutation is a conditional UPDATE via conditional_update_row: the
fight sequence claims the cooldown first, then spends coins, then lands
the damage, compensating earlier steps on any later refusal so a crash
costs a turn, never coins. Resolution is lazy on read (no cron):
an exactly-once CAS computes the winner in the statement, awards XP
(participation, winner bonus, top damage dealer bonus; draws pay
participation only), emits the result event and notifies fighters. The
OpinionWarService backstop resolves unviewed wars and sends
fight-ready notifications, exactly-once via a marker CAS.

Fan-out: battle notification type, four badges, audit keys
(battle.create/join/switch/fight/resolve), Devii actions (join/fight
confirm-gated), API docs group, docs prose page, sitemap and topnav
entries, REPORTABLE_TARGETS registration, post-delete cascades,
README and nested CLAUDE.md documentation.

Verified with the four-layer procedure: property checks over the full
damage domain, 1200-step stateful fuzz (hp-sum invariant, coins never
negative, resolved totals frozen), and real 8-process races proving
exactly-once semantics for concurrent fights, double-spends across two
wars, resolution XP and double-joins. Persisted tests in
tests/unit/services/opinionwar, tests/api/battles, tests/e2e/battles
and tests/api/posts/create.py.

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

README.md

@@ -97,6 +97,7 @@ devplacepy/
 | `/leaderboard` | Contributor ranking by total stars earned |
 | `/game` | **Code Farm** cooperative idle game (member-only): plant projects that build over real time, harvest coins and XP, upgrade CI, buy plots, and water friends' builds at `/game/farm/{username}`. Live over pub/sub; every endpoint negotiates JSON |
 | `/quizzes` | **Quizzes**: author quizzes, play them, and climb the cross-quiz scoreboard. Three-column hub with filters (`all`/`todo`/`done`/`mine`/`drafts`), search, per-viewer state badges, and the scoreboard rail; `/quizzes/{slug}` detail, `/quizzes/{slug}/edit` builder, `/quizzes/{slug}/attempts/{uid}` player, `/quizzes/scoreboard` JSON. Publishing is permanent. Every endpoint negotiates JSON |
+| `/battles` | **Opinion Wars**: week-long two-faction battles attached to posts, started from the composer's *Start Opinion War* builder. Members join a side and fight once a day (25 Code Farm coins, level-weighted damage); the pixel-art battle card shows live HP bars, a countdown, top contributors and an event ticker. `/battles` lists battles (`active`/`ended`/`mine` + search); `/battles/{uid}` state, `/battles/{uid}/events` replay, `/battles/{uid}/join` and `/battles/{uid}/fight` actions |
 | `/avatar` | Multiavatar proxy with in-memory cache |
 | `/issues` | Issue tracker backed by Gitea: list/detail/comment/status, AI-enhanced filing, an admin planning report over a selectable set of open tickets (each ticket's full text reproduced verbatim so the document hands straight to a coding agent), and file attachments on open issues and comments (mirrored to the Gitea tracker) |
 | `/admin/services` | Background service management (start/stop, config, status, logs) |
@@ -169,6 +170,25 @@ scoreboard on the right. Guests read published quizzes and see the board; they c
 Retention: completed attempts are permanent; abandoned and expired ones are garbage-collected by
 `devplace quiz prune`.
 
+## Opinion Wars
+
+**Opinion Wars** (`/battles`) are week-long two-faction battles attached to posts, in the spirit of
+old eRepublik battles: settle tabs-versus-spaces by showing up daily and fighting for your side.
+
+- **Start one from the composer.** The *Start Opinion War* button next to *Add poll* names the two
+  factions; the battle runs for exactly 7 days from the moment the post is published.
+- **Join and fight.** Any signed-in member picks a side and may fight once every 24 hours per
+  battle. A fight costs 25 Code Farm coins and deals deterministic, level-weighted damage
+  (100 HP + 10 per site level, capped at level 20) - no randomness, dedication wins wars.
+- **Defection is allowed.** Switch factions any time; damage already dealt stays where it landed.
+- **Live pixel-art card.** The battle renders on the post as a CSS pixel-art battlefield with HP
+  bars, a countdown, your rank, top contributors and a live event ticker (joins, defections,
+  fights, lead changes) over pub/sub with an incremental replay fallback.
+- **Rewards.** When the week ends the bigger total wins: every fighter earns XP, the winning side
+  and the top damage dealer earn bonuses, and battle badges (*Instigator*, *First Blood*,
+  *War Veteran*, *Champion*) mark the milestones. Notifications cover lead changes, the result and
+  your next fight being ready.
+
 ## Code Farm
 
 The **Code Farm** (`/game`) is a cooperative idle game in the spirit of Farmville, themed for developers. Each member owns a farm of plots and plays asynchronously - nothing has to happen in real time.