Sync dmrg tutorials 03-06 with alpsim.github.io reference

[marcusr2ML]

Renumber the DMRG tutorial directories to match the layout in ALPSim/alpsim.github.io content/en/tutorials/dmrg/codes:

dmrg-01-dmrg -> dmrg-03-ground-state-energies
dmrg-02-gaps -> dmrg-04-gaps
dmrg-03-local-observables-> dmrg-05-local-observables
dmrg-04-correlations -> dmrg-06-correlations

dmrg-04-gaps:

• spin_one_half_gap: MAXSTATES 40 -> 100
• add spin_one_half_multiple (used by the exercise in dmrg04)

dmrg-05-local-observables: the tutorial now splits the S=1 chain into a uniform and a spin-1/2-capped variant.

• add build_lattice.py, spin_one_uniform{,.py}, spin_one_capped{,.py}
• spin_one_half{,.py}: CONSERVED_QUANTUMNUMBERS "Sz" -> "N,Sz", SWEEPS 4 -> 6, L 32 -> 64, MAXSTATES 40 -> 100

dmrg-06-correlations:

• spin_one{,.py}: fix lattice name ("especial edges 32" ->
  "special edges 64"), CONSERVED_QUANTUMNUMBERS -> "N,Sz", replace the MAXSTATES scan with L=64/MAXSTATES=100, SWEEPS 4 -> 6
• spin_one_half{,.py}: same quantum-number and L/MAXSTATES updates; loop over Sz_total in {0,1,2} instead of MAXSTATES
• my_lattices.xml: whitespace fix on the tag

Summary

Type of change

• Bug fix
• New feature or algorithm
• Documentation or tutorial improvement
• Build system / dependency update
• Refactor (no behaviour change)
• Other:

Testing

• Existing tests pass (ctest --output-on-failure)
• New tests added for changed behaviour
• Results verified against known reference values or published results
• Tested on Linux
• Tested on macOS

For simulation code changes

• Physical results match expected behaviour (describe briefly below)
• Parameter files / input format changes are documented
• Relevant tutorial or documentation updated

Checklist

• CI passes (build + tests on all platforms)
• No new compiler warnings (-Wall -Wextra)
• Code follows the style of the surrounding code
• Commit messages are descriptive and in the imperative mood

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