docs(web-ui): sync dashboard docs after the SYST3M → C0R3 page move

The C0R3 page PR moved the SYST3M tab off the dashboard onto the
standalone /core.html page, leaving the web-ui docs describing a tab that
no longer exists.

- dashboard.md: retitle the "SYST3M tab" section to "C0R3 page
  (/core.html)" and reframe its intro — it's now a standalone page off the
  H0M3 hub with a createTabStrip sub-tab nav (default R3BU1LD QU3U3), its
  own core.js bundle on /dashboard/stream; the dashboard keeps only the
  rebuild-queue state for the SW4RM "building…" badges.
- correct the chrome tab-strip list to the actual in-page tabs
  (SW4RM / Y3R C4LL / P3RM1SS10NS / SCH3DUL3S) and note SYST3M / ST4TS /
  S3TT1NGS / FL0W / L0GS / M4TR1X are all standalone pages off H0M3.
- fix the container-load poll reference (core.js, while the C0NT41N3R
  L04D sub-tab is active) and the stray "SYST3M ›" panel references.
- drive-by: the schedules endpoint doc said "SYST3M scheduled-prompts
  panel" — it's the SCH3DUL3S panel; corrected.
- web-ui.md index: same tab-list correction + C0R3 page pointer.

docs/web-ui.md

@@ -13,7 +13,8 @@ This doc has been split for readability. Pick the section you need:
   per-agent relative paths, `data-async` form pattern, side panel,
   atomic repaint.
 - **[Dashboard layout](web-ui/dashboard.md)** — tab contents
-  (SW4RM, Y3R C4LL, SYST3M, P3RM1SS10NS, SCH3DUL3S, P33RS, S3TT1NGS), container row,
+  (SW4RM, Y3R C4LL, P3RM1SS10NS, SCH3DUL3S) + the standalone C0R3 page
+  (`/core.html` — the old SYST3M panels), container row,
   topology tree, selection bar, approval card, browser
   notifications, dashboard endpoints + event channel.
 - **[Per-agent page](web-ui/agent.md)** — header, main terminal,