Add a compact Presentazione tour of verified algorithms

[xtraid]

Technical explanations and their supporting visuals were spread across Pages. Add /presentazione/ as a compact technical tour, placing concrete solver states and construction visuals beside short explanations and links to authoritative details. Preserve all 40 existing routes, Reference, Evidence and run dossiers; Pages now has 41 routes.

• Reuse observed propagation/MRV states and Yang–Zhang construction visuals. Show decision, conflict, rollback and the next candidate using five frames from the existing search-UNSAT capture, separately from the unchanged canonical SAT example.
• Add one small didactic dependency SVG; link the complete Worked Example and existing six-mechanism optimized summary.
• Keep prose narrow, allow wider tour figures, and provide full-size links and locally collapsed technical provenance. Add navigation anchors and visual links to the serial implementation guide.
• Validate the explicit reused frames through existing ownership, manifest and replay checks. Production renderer/selector, solver semantics, schemas and all 87 canonical assets remain unchanged.

Authored changes: 15 files, +604/−5 lines, including the SVG. Separately, five re-exported PNGs and six unchanged capture JSON files add 2,012,876 bytes.

Validation on the reviewed inputs: 26 checker tests, 24 trace/re-export tests, Jekyll and generated HTML checks (41 pages, 919 references), 16 browser cases, and two desktop/mobile journeys of 26 steps each at DPR 2. Independent cumulative review found no issues.