Builtin OfficeCLI skills still instruct double page breaks

## Problem

The builtin OfficeCLI DOCX skills still instruct agents to apply both an explicit `pagebreak` and `pageBreakBefore=true` at the same logical boundary. In Word and WPS this can produce an extra blank page.

OfficeCLI tracked and fixed this behavior in iOfficeAI/OfficeCLI#191 and iOfficeAI/OfficeCLI#193, but the corresponding builtin assets in AionCore have not picked up that fix.

## Current behavior

Verified on current AionCore `main` (`6e04e741c42425072a8296fdacd95e5d1261d4d7`) and release `v0.1.65`:

- `crates/aionui-app/assets/builtin-skills/officecli-docx/SKILL.md` says `Apply BOTH` and provides a two-mechanism example.
- `crates/aionui-app/assets/builtin-skills/officecli-academic-paper/SKILL.md` inherits the stale belt-and-suspenders rule.
- The DOCX skill also retains the static TOC fallback removed by the same upstream fix.

A deterministic check is:

```bash
rg -n "Apply BOTH|belt-and-suspenders|Static TOC fallback" \
crates/aionui-app/assets/builtin-skills/officecli-docx/SKILL.md \
crates/aionui-app/assets/builtin-skills/officecli-academic-paper/SKILL.md
```

## Expected behavior

Mirror the focused changes from iOfficeAI/OfficeCLI#193:

- use exactly one page-break mechanism per logical boundary;
- remove examples that set `pageBreakBefore` on a newly inserted page-break paragraph;
- retain a live TOC with `updateFields=true` rather than guessed static page numbers;
- update the academic-paper references to the corrected base rules.

## Scope

Builtin Skill documentation only. No Rust behavior or user-visible UI changes.

Start with crates/aionui-app/assets/builtin-skills/officecli-docx/SKILL.md and officecli-academic-paper/SKILL.md, then run the provided rg check to locate the stale rules and examples. Mirror the focused changes from iOfficeAI/OfficeCLI#193: use one page-break mechanism, remove the static TOC fallback, retain a live updating TOC, and update the academic-paper references.

Written by the indexing model from the issue text.