docs: complete thermal-fin MLOps project specification

[prudhomm]

Summary

• clarify the M2 hierarchy: preparation session, MLOps mini-project, and semester continuation
• explain the engineering motivation for automating high-fidelity simulation-to-surrogate workflows
• state the 3D nondimensional thermal problem, interface continuity, boundary conditions, weak form, and root-temperature output using proper AsciiDoc LaTeX math
• fix the parameter map mu=(L,t,Bi) and keep generated material properties fixed throughout the campaign
• document the Feel++ PostProcess.heat.Measures.Statistics JSON needed to extract mean_root_temperature on Gamma_root
• harmonize lifecycle, dataset, inference, optimisation, and navigation terminology

Validation

• full npm run antora build
• 6 teaching notebooks bundled and verified
• 157 HTML pages checked with 0 broken local links
• 124 pages checked for breadcrumbs/pagination with 0 failures
• git diff --check