WIP: Filling in Delphes Fast Simulation step of tutorial

[bistapf]

Sim/ee: translate FCC-hh Delphes tutorial to FCC-ee IDEA fast-sim

Draft — work in progress, opening early to track progress. Translating the old FCC-hh-specific fast-sim tutorial section to the FCC-ee IDEA chain (WHIZARD/Pythia → Delphes IDEA → EDM4hep), following the Gaudi-based k4SimDelphesAlg steering approach rather than the old DelphesPythia8_EDM4HEP executable.

To do - completion of first version of tutorial text

• Fill in steering-file walkthrough: guide students through the delphes_mumuH_IDEA.py skeleton parameters, and give the k4run command to actually launch the fast sim
• Add a short "what to expect while it runs" note (what output/logging they'll see, roughly how long it takes)
• Write "Understanding the Delphes parametrization" section (moved to right after the run step): finish the IDEA card walkthrough already started, including the track covariance matrix approach, with guided questions that trace one specific reco chain through the card
• Write "Understanding edm4hep datamodel collections" section (moved after the Delphes section): how to inspect a file's collections, tying it back to picking collection names for the steering file
• Add task: trim the output-settings file (edm4hep_IDEA.tcl) to drop collections we don't need downstream (e.g. Jet)
• Decide whether to keep the closing "make some plots directly from EDM4hep" section, and write it if so

Misc fixes and updates todo

• Resolve remaining inline placeholders/TODOs (ADD LINKS TO MATCHING DOC!, doc links, etc.)
• Fix deprecation warning in edm4hep_IDEA.tcl: k4SimDelphes::getEDM4hepOutputSettings | MCRecoAssociationCollectionName is deprecated, use RecoMCParticleLinkCollection instead
• Keep Sim/ee/solutions/ in sync with the final exercise text
• Clean up Sim/ee/ working files before merge: add .gitignore for generated .root output, reconcile the duplicate filled-in steering scripts (delphes_mumuH.py / delphes_mumuH_SOL.py) into solutions/, and decide whether the local delphes_card_IDEA.tcl copy should be vendored or left out per the stack-version convention
• Provide a path to a centrally produced input file here in case student was not able to complete previous step