docs(calm-suite): A2 — remove hackathon ADRs and orphan examples

Implements STRUCT-02 (Track A — finos#2649). Removes pure hackathon residue with zero external code references.

Deleted (13 paths):
- 10 ADRs in docs/docs/calm-studio/adrs/0001-0010-*.md — pre-FINOS decision records authored during hackathon, not user-facing
- docs/docs/calm-studio/adrs/index.md — ADR sidebar landing (now stub)
- calm-suite/calm-studio/examples/architecture_calm.json — orphan; no code imports
- calm-suite/calm-studio/examples/aws_multi_tier_calm.json — orphan; no code imports

Updated:
- docs/sidebars.js — removed ADRs category block (lines 155-171) so Docusaurus build does not 404 on deleted slugs

Verified safe to delete:
- `grep -rE '/adrs/' docs/docs --include='*.md'` excluding adrs/ itself returns no matches — no internal doc links point at these ADRs
- `npm run build --workspace docs` exits 0 after deletion + sidebar edit

Deferred to later phases (referenced by production code or framework-generated assets — would break behaviour if deleted now):
- 3 demos in calm-suite/calm-studio/apps/studio/static/demos/{aws-multi-tier,ecommerce,opengris-local-cluster}.calm.json — actively imported by apps/studio/src/lib/toolbar/Toolbar.svelte and listed in SvelteKit-generated apps/studio/.svelte-kit/non-ambient.d.ts. Defer to Phase 10 (STUDIO-06 — Hub-sourced templates) where Hub patterns replace them.
- calm-suite/calm-guard/examples/ — DEMO_ARCHITECTURES is imported by calm-guard/src/components/calm/architecture-selector.tsx and calm-guard/src/components/dashboard/header.tsx. Defer to Phase 10.
- calm-suite/calm-studio/docs/{AIGF_CATALOGUE.json,REQ_fluxnova_aigf_integration.md,CALM_1.2_CONTROLS_SCHEMA.md,images/} — cited in calm-core/src/aigf/{catalogue,mappings,types}.ts source comments AND in calm-suite/calm-studio/AGENTS.md. Defer to Phase 13 (DOCS-01) where the comments + AGENTS.md references are cleaned up together with docs consolidation.

Refs finos#2649 (Track A), finos#2600 (parent epic).

Signed-off-by: Gourav Shah <gjs@opsflow.sh>

Author: gjs-opsflo