feat(stats): add an 'all' time range to agent + hive stats

Adds a Window::All option to the per-agent stats page and the hive-wide
rollup, selectable as a new 'all' tab on both.

- hive-ag3nt (per-agent, time-bucketed): All ranges from MIN(started_at)
  to now (fallback to now on an empty table) with an adaptive bucket
  width laddered by span — hourly <=2d, daily <=90d, weekly <=2y, 30-day
  beyond — so the trend series stays bounded (~<=104 buckets) at any age.
- hive-c0re (swarm rollup, not time-bucketed): All sets from=0 so the
  aggregate covers every recorded turn across all agents.
- frontend: an 'all' button on both the agent stats and dashboard hive
  stats window selectors (createTabStrip + fetch already pass the window
  string through, so no JS change needed).

cargo check passes on both crates; FE builds clean. Fixes #1919.

frontend/packages/agent/src/stats.html

@@ -23,6 +23,7 @@
     <button type="button" data-tab="3d">last 3d</button>
     <button type="button" data-tab="7d">last 7d</button>
     <button type="button" data-tab="30d">last 30d</button>
+    <button type="button" data-tab="all">all</button>
   </div>
 
   <div class="summary" id="summary"></div>