assistant: teach the agent about Search admin

Bring the LLM agent's prompts and tools current with the new /search
section and arcadia-search admin sidecar:

- New tools in admin-tools.ts:
  - list_search_corpora: enumerate tenants + corpora with build status,
    so the agent can pick a real corpus instead of guessing.
  - rebuild_search_corpus(tenant, corpus): isWrite=true, surfaces a
    confirm card. Use after uploads or when results look stale.
- search_kb description updated: names docs / operator-tools / files
  explicitly, and points at list_search_corpora when unsure.
- ARCADIA_KNOWLEDGE: adds search-corpus terminology, /search route,
  and a one-liner pointer to the three new tools.
- assistant.tsx UI_CONTROL_PREFACE: nav-search added, full Search
  page action catalog (search-refresh / -restart / -new-tenant /
  -new-corpus, corpora-search, per-row corpus-{t}-{c}-{rebuild,edit,
  delete,actions}, tenant-{id}-delete, dialog form fields). Recipe
  for the manual rebuild path, plus a note steering the agent to
  the rebuild_search_corpus tool by default.
- search.tsx publishes a "search" surface to admin-context with
  tenants + corpora summary, so the agent gets live state without
  needing a tool call when /search is mounted.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/routes/assistant.tsx

@@ -53,7 +53,7 @@ Rules:
 
 Known action ids across the app (use these even if not in "Available actions" — the page may not be mounted yet):
 
-Sidebar / nav: nav-overview, nav-tenants, nav-resources, nav-activity, nav-assistant, nav-library, nav-settings, sidebar-toggle, mobile-nav-toggle
+Sidebar / nav: nav-overview, nav-tenants, nav-resources, nav-activity, nav-search, nav-assistant, nav-library, nav-settings, sidebar-toggle, mobile-nav-toggle
 Appbar: appbar-search (input), appbar-scripts, appbar-font-size, appbar-surface, appbar-background, theme-toggle, appbar-notifications, appbar-avatar
 Account menu (after click appbar-avatar): avatar-profile (→ /profile), avatar-settings, avatar-help, avatar-signout
 Profile page: profile-avatar-upload, profile-avatar-remove, profile-name, profile-email, profile-title, profile-bio, profile-signature, profile-default-agent, profile-save, profile-revert, profile-reset
@@ -66,6 +66,7 @@ Assistant page: assistant-model, assistant-agent, assistant-thread, assistant-th
 Library page: library-search, library-open-<id>, library-copy-<id>, library-download-<id>, library-delete-<id>
 Resources page: resources-search, resources-new-name, resources-create, resources-status-<id>, resources-delete-<id>
 Tenants page: tenants-refresh, tenants-search (input), tenants-create. Per-row (use the tenant's slug — see the "tenants" surface in Admin context for available slugs): tenant-<slug>-actions (open the kebab first), tenant-<slug>-suspend, tenant-<slug>-activate, tenant-<slug>-deactivate. Recipe to suspend a tenant: click nav-tenants, wait_for tenants-refresh, click tenant-<slug>-actions, wait_for tenant-<slug>-suspend, click tenant-<slug>-suspend.
+Search page (/search — manage arcadia-search tenants and corpora): search-refresh, search-restart (with confirm), search-new-tenant, search-new-corpus, corpora-search (input). Per-tenant chip: tenant-<id>-delete. Per-corpus row (id is "<tenant>-<corpus>"): corpus-<tenant>-<corpus>-actions (kebab), corpus-<tenant>-<corpus>-rebuild, corpus-<tenant>-<corpus>-edit, corpus-<tenant>-<corpus>-delete. New-tenant dialog: tenant-form-id (input), tenant-form-cancel, tenant-form-save. New/edit-corpus dialog: corpus-form-tenant (select, only when creating), corpus-form-config (textarea, JSON), corpus-form-cancel, corpus-form-save. Recipe to rebuild a corpus: click nav-search, wait_for search-refresh, click corpus-<tenant>-<corpus>-actions, wait_for corpus-<tenant>-<corpus>-rebuild, click corpus-<tenant>-<corpus>-rebuild. (NOTE: prefer the \`rebuild_search_corpus\` tool over UI-driving for rebuilds — it's atomic and gives a structured result; UI-drive only when the user explicitly wants to see it happen.)
 Login page: login-email, login-password, login-submit
 Notifications popover: appbar-notifications (open), notif-mark-all-read, notif-clear, notif-open-<id>, notif-dismiss-<id>
 Create a notification (hidden bridge — always available, even when not visible): fill the four hidden inputs, then click the submit button. Recipe:
@@ -113,7 +114,7 @@ function buildAdminPreface(activeAgent: Agent | undefined, uiControl: boolean):
   const ctx = formatAdminContextForPrompt()
   const parts = [
     "You are the operator's assistant inside Arcadia Admin. Be precise and direct. You have native function tools attached to this conversation — call them whenever the user asks about live platform state (counts, statuses, listings, lookups). Never invent tenant slugs, user counts, or statuses; if you need data, call a tool.",
-    "Two retrieval surfaces exist for documentation/knowledge: `search_docs` (browser-side, BM25 over the bundled arcadia docs — fast, always available, small corpus) and `search_kb` (server-side, BM25 over arcadia-search — same docs as `corpus=docs` for parity, plus larger and additional corpora as the operator adds them). For questions about the bundled arcadia docs either is fine; prefer `search_kb` when you want richer hits or when the user is asking about content that wouldn't be in the bundled docs (uploaded files, tenant-specific knowledge). When `search_kb` returns a chunk_id you want to expand, call `read_chunk(chunk_id, corpus)`.",
+    "Two retrieval surfaces exist for documentation/knowledge: `search_docs` (browser-side, BM25 over the bundled arcadia docs — fast, always available, small corpus) and `search_kb` (server-side, BM25 over arcadia-search — `docs` (arcadia parity), `operator-tools` (arcadia-search + arcadia-admin admin docs), `files` (uploaded files), plus any custom corpora the operator adds via /search). For questions about the bundled arcadia docs either is fine; prefer `search_kb` for richer hits or for content outside the bundled docs (uploaded files, the admin tooling itself, tenant-specific knowledge). If unsure what corpora exist, call `list_search_corpora`. When `search_kb` returns a chunk_id you want to expand, call `read_chunk(chunk_id, corpus)`. When the operator says results look stale or after they've uploaded new files, call `rebuild_search_corpus(tenant, corpus)`.",
     RICH_OUTPUT_PREFACE,
     ARCADIA_KNOWLEDGE,
     persona,