Refactor: split console-instances.js (957 lines) into -core + -board

[serge-ivo]

Problem

console-instances.js is 957 lines mixing instance load/open/tabs/KB/chat with the kanban board + runtime-task detail. High churn, hard to reason about.

Approach (plan ready)

Split into console-instances-core.js (load/open/tab-switch/KB/chat/settings) and console-instances-board.js (kanban, runtime task cards/detail, board polling, apply checklist). Same pattern just used for console-coding.js: ALL shared let state declared in ONE file (classic scripts share top-level let), functions split by domain. Wire build.js + host routes + index.html script order (core before board before apps). e2e server regex already matches.

Acceptance

• No behaviour change; the "scripts parse + load without page errors" guard test stays green; full e2e green.

Risk

Low — same verified approach as the coding split (#commit 3e423dd). Main risk is duplicate let → caught by the guard test.

[serge-ivo]

Obsolete — superseded by the console rewrite. console-instances.js (the 957-line file this asked to split) no longer exists; the console is now React (store/console/src/), with instances split across pages/InstanceDetail.tsx, tabs/BoardTab.tsx, tabs/CodingTab-surface, etc. The 'split -core + -board' goal was effectively delivered by that rewrite. Closing as not-planned (nothing left to split). Broader file-size refactoring is tracked in #125.