Build AgentGuide — versioned CLAUDE.md maintenance

The app-owned agent guide at every board root (DESIGN/08 ▸ The agent
guide): version-gated by a first-line marker (v5, superseding the
pathfinder's v4 guides on real boards), rewritten when missing or older,
byte-for-byte untouched when current or newer. A markerless CLAUDE.md is
displaced to CLAUDE.user.md when that name is free — never clobbered —
and the guide write is skipped with a log when it isn't. Symlinks,
folders, and read-only volumes are skipped in silence; the write rides
performWrite's bracket as an app-mediated Writer operation (new
WriteOperation.agentGuide), so the echo lands appMediated and the
Pro-era committer can attribute it honestly later.

Hooked at store acquire (beside the loose-file relocation, after the
watcher exists) and on every successful reload — the guide self-heals
from foreign deletion or rollback, pre-wiring 06's acknowledged undo
bounce. The refresh memo arms before each attempt and clears on a
successful write, so a failing write can't hot-loop and a foreign
deletion stays healable. First-line-only marker parsing (no Regex);
guide content is one swappable literal, finalized under the next card.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

Kanban/LiveStore/BoardStoreRegistry.swift

@@ -217,6 +217,12 @@ public final class BoardStoreRegistry {
         // thereafter re-fires it from `BoardStore.land`; this call is only the one the opening walk
         // would otherwise have no reload behind.
         store.relocateLooseCardFiles()
+        // The agent guide's first firing (08-agent-integration.md ▸ The agent guide), here for the
+        // same reason and with the same timing as the relocation above: a board opened with no
+        // `CLAUDE.md`, or with one an older version wrote, gets the current guide now — as a
+        // bracketed app write with a reload behind it, never as a write into a board nothing is
+        // watching. Every reload thereafter re-checks it from `BoardStore.land`.
+        store.refreshAgentGuide()
         return store
     }