docs(home): honest home-page copy + move Performance & Benchmarks to sidebar bottom

[bedus-creation]

Context

PR #56 was squash-merged into main and already carried most of the task/perf-benchmark-methodology work (benchmark page, real web-frameworks numbers, Observability→AI module swap, removal of the SLA/P99 hero stats, and the sidebar entry). This PR (base main, not the merged #56) brings over the remaining meaningful changes from that branch that main did not yet have, plus the sidebar move requested in task #673.

Changes

1. Remaining honest home-page copy (not covered by #56)

• CoreModules.vue — drop the unsubstantiated "fastest possible execution path" claim from the Asynchronous Core module.
• HeroSection.vue — reframe the hero description around "batteries-included" instead of "high-performance boilerplate engineered for speed".
• SiteFooter.vue — same de-hyping for the footer tagline and copyright line.

2. Sidebar reorder (task #673)

• Move Performance & Benchmarks out of the Digging Deeper group to a standalone entry at the very bottom of the docs sidebar (after Testing).

Deliberately excluded

To avoid reverting decisions main already made independently in #56, this PR does not touch:

• The AI module title (main chose "AI & Agents"; the old branch had "AI & MCP").
• The hero stats block (main removed it entirely; the old branch re-added a "100% Test Coverage" stat).
• Docs pages where main is ahead of the old branch (docs/ai/agent.md, docs/fastapi.md, docs/getting-started.md, etc.) — diffing the raw branch would have reverted that newer work.

Verification

• vitepress build completes successfully with the new sidebar structure.

[bedus-creation]

Code Reviewer verdict: APPROVE ✅ (posted as comment — GitHub blocks self-approve on this account)

Reviewed the full diff and verified locally:

• vitepress build completes successfully on the PR branch (branch task/673-perf-leftover-sidebar).
• Sidebar reorder is structurally valid: Performance & Benchmarks moved from Digging Deeper to a standalone top-level entry after Testing. Exactly one /docs/benchmarks reference remains (no duplicate); target docs/benchmarks.md exists (no dead link).
• Home-copy de-hyping is accurate/grammatical; no residual "high-performance"/"fastest"/"engineered for speed" claims remain in home components.
• Confirmed it does NOT revert #56 decisions: "AI & Agents" title preserved, hero stats not re-added.

No blockers — safe to merge once QA passes.