feat: add live views support

[emrberk]

Adds live views to the Web Console as a first-class schema object.

Live views

• The schema tree gains a Live views folder with its own icon, search, tooltips and context menu.
• The details drawer supports live views: status, base table, DDL and columns, plus a monitoring tab with freshness (unflushed transactions, time since last flush, writer stall) and in-memory tier (rows, footprint, dropped rows) metrics.
• Invalid, state-unreadable and version-unsupported live views raise a critical banner with recovery guidance, both in the tree and in the drawer.
• A suspended live view can be resumed from the tree; the console issues ALTER LIVE VIEW '<name>' RESUME WAL.
• The AI assistant and MCP tools can list, explain and inspect live views alongside tables, views and materialized views.

Other user-visible changes

• Catalog counters keep full 64-bit precision. LONG columns from tables(), materialized_views() and live_views() are read as bigint, so large row counts and transaction numbers are no longer rounded in the drawer or in AI prompts.
• Storage policy is read from the storage_policies catalog instead of being parsed out of DDL text, so the Details tab reflects policy changes live, including a disabled policy.
• The drawer reports unreachable metadata explicitly. Each metadata source shows an "Unavailable" state and retries on its own, keeping the last good values rather than blanking the panel.
• The write amplification warning now fires at 3.0x, up from 2.0x, to cut noise on tables where O3 merges are expected.
• The schema filter no longer crashes when the query contains a regular-expression character such as ( or [.
• Invalid view messages no longer print null when the server reports no invalidation reason.