chore: bump workspace version to 0.20.0

[nick-youngblut]

All 16 versioned workspace members, pyscx/pyproject.toml and
rscx/DESCRIPTION; tests/scx-integration-tests stays at 0.0.0. README's
scx-cli download snippet follows. (ROADMAP.md no longer exists, so there is
no date stamp to move.)

0.20.0 collects the merged PRs since 0.19.0 (#544-#561):

• CSC sidecar series: one-pass bucketed CSC builder (sparse: one-pass CSC sidecar builder, replacing the per-chunk transpose #555); build-csc as an
  in-place, rollback-able append (ops: build-csc appends its CSC sidecar in place instead of rewriting the file #556); same-pass CSC build on ingest and
  carry-through on rewrite ops (ops+convert: build the CSC sidecar in the same pass, and carry it through rewrite ops by default #557); parallel CSC build and csc="auto" as
  the ingest default (sparse+format-io+engine: parallel CSC build, and csc="auto" as the ingest default #558); CSC dispatch for row-indexed transforms and
  row-filtered / gene-subset handles (accel: let CSC dispatch serve row-indexed transforms #553, accel: serve CSC dispatch on a row-filtered or gene-subset handle #554); CSC route coverage and the
  exact-nnz Wilcoxon kernel as the 1-vs-rest CSC default (accel: promote exact-nnz Wilcoxon to the CSC default, and fix the two CSC routes that lost for a reason #559)
• Correctness: Leiden parallel local moving keeps decliners eligible (accel: mark every evaluated node stable in Leiden's parallel local moving #544);
  five CPU-accelerator parity / convergence fixes (accel: five CPU-accelerator numerical-parity and convergence fixes (review §7.3, §7.10, §7.11, §7.15, §7.17) #548); GPU cuVS stream sync,
  reduction determinism, decoder bounds and VRAM accounting (gpu: cuVS stream synchronization, reduction determinism, decoder bounds, and VRAM accounting #549); CLI
  destination-overwrite safety and MTX multimodal / streaming / integer
  integrity (cli+mtx: destination overwrite safety, and MTX multimodal / streaming / integer integrity #550); unscoped whole-matrix reads of a multimodal file refused
  (format: refuse an unscoped whole-matrix read of a multimodal file, and name the CSR structural checker #551); dictionary (categorical) output from append / merge / merge
  --sort-by (ops: dictionary output from append, merge and merge --sort-by #546) and scx sort's obs spill path (ops: dictionary output from scx sort's obs spill path #547)
• Benchmarks and docs: four community analytical benchmarks (bench: four community analytical benchmarks, gated and documented #552), laptop-test
  recapture (bench: recapture the laptop-test pipeline on the CSC DE route #560), README refresh (docs: refresh the README feature surface, and correct two stale build-csc claims #545), docs split into per-topic
  directories (docs: split scanpy/api/performance into per-topic directories, and clean up outdated docs #561)

Behaviour changes worth calling out in the release notes:

• csc="auto" is the ingest default on every entry point and preset
  (from_mudata keeps off): files with n_obs >= 50000 and
  n_vars >= 5000 now get a CSC sidecar, costing ingest wall time and
  +42-71 % on disk. --csc off / csc="off" opts out (sparse+format-io+engine: parallel CSC build, and csc="auto" as the ingest default #558).
• Rewrite ops carry the CSC sidecar by default (compact, merge,
  optimize, sort, subset), rebuilt from the output's own shards;
  --csc carry|always|off. --rebuild-csc / rebuild_csc=True are
  deprecated aliases for always (ops+convert: build the CSC sidecar in the same pass, and carry it through rewrite ops by default #557).
• scx build-csc appends in place rather than rewriting the file, and
  scx rollback removes the sidecar (ops: build-csc appends its CSC sidecar in place instead of rewriting the file #556).
• Ten CLI subcommands no longer silently overwrite an existing destination;
  --force is required (convert, merge, subset, query --output, upgrade,
  cloud-optimize, explode, pack, pull; compact / optimize / sort migrated onto
  the same guard) and is refused where nothing is written (cli+mtx: destination overwrite safety, and MTX multimodal / streaming / integer integrity #550).
• MTX: a declared-integer MTX with a value past 2^24, a non-integral
  value or nan/inf is refused on ingest (--allow-lossy restores the old
  behaviour); multimodal MTX export requires a modality (pyscx.to_mtx gains
  modality=); export streams one shard at a time (cli+mtx: destination overwrite safety, and MTX multimodal / streaming / integer integrity #550).
• An unscoped whole-matrix read of a multimodal file raises
  MultimodalRequiresModality instead of folding every modality into one
  n_obs x n_modalities-row answer — to_anndata(), to_memory(),
  read_all_csr_shards*, scx pull --filter (format: refuse an unscoped whole-matrix read of a multimodal file, and name the CSR structural checker #551).
• Numerical changes: UMAP init scale and random_init now match
  umap-learn, the kNN sigma search, and NB-GLM dispersion shrinkage (the
  above_min_disp residual filter always runs; new disp_outlier_sd=2.0
  carve-out, None disables only the carve-out) (accel: five CPU-accelerator numerical-parity and convergence fixes (review §7.3, §7.10, §7.11, §7.15, §7.17) #548); parallel Leiden
  labels change (accel: mark every evaluated node stable in Leiden's parallel local moving #544).
• Wilcoxon on the CPU CSC route defaults to the exact-nnz kernel (route id
  cpu_csc_nnz); SCX_ACCEL_WILCOXON_NNZ=0 restores densify (cpu_csc), and
  reference= / rankby_abs=True still use densify (accel: promote exact-nnz Wilcoxon to the CSC default, and fix the two CSC routes that lost for a reason #559).
• Categorical obs columns keep their declared categories, unused levels and
  ordered bit through append / merge / sort (ops: dictionary output from append, merge and merge --sort-by #546, ops: dictionary output from scx sort's obs spill path #547).

No benchmark recapture for this release.

Pre-release gate on this tree: cargo fmt --check; cargo clippy --workspace --exclude rscx --all-targets -D warnings; cargo test --workspace --exclude rscx (4,220 passed, 0 failed); cargo test -p scx-convert --features hdf5
(474 passed); cargo test -p scx-cli --features hdf5 -- --test-threads=1 (253
passed); maturin develop --release + pytest tests/ (3,247 passed, 140
skipped, 2 xfailed; pyscx.__version__ == "0.20.0"). Not run: rscx tests,
--features cloud, GPU pytest, fuzzing, benchmarks.

🤖 Generated with Claude Code

https://claude.ai/code/session_01RwRKstgr4TNkXhLhkQwmjA

[gemini-code-assist]

Code Review

This pull request updates the version of the SCX project and its various sub-crates and bindings from 0.19.0 to 0.20.0 across all configuration files, lockfiles, and documentation. There are no review comments, and I have no feedback to provide.