feat(encode): add parity helpers

[lmeyerov]

Summary

• Add direct public encode helpers for edge size/weight plus point/edge opacity, label, and title.
• Add GFQL call() safelist/runtime/type parity for the new encode entry points.
• Extend apply_encodings() key introspection and schema artifacts without adding unsupported React component props; label/title helpers are raw column binding only because Graphistry upload rejects label/title complex encodings.
• Add anchored validator and direct serialization coverage.

Closes #1253

New Encode Entry Points

• encode_edge_size: maps edge column values to size encodings with numeric categorical/default mappings.
• encode_edge_weight: maps edge column values to weight encodings with numeric categorical/default mappings.
• encode_point_opacity: maps node column values to opacity encodings with numeric categorical/default mappings.
• encode_edge_opacity: maps edge column values to opacity encodings with numeric categorical/default mappings.
• encode_point_label: raw-binds the node label column; categorical/default mappings are rejected before complex encoding creation.
• encode_edge_label: raw-binds the edge label column; categorical/default mappings are rejected before complex encoding creation.
• encode_point_title: raw-binds the node title column; categorical/default mappings are rejected before complex encoding creation.
• encode_edge_title: raw-binds the edge title column; categorical/default mappings are rejected before complex encoding creation.

Validator-Error Samples

• encode_edge_size: Invalid value for parameter 'categorical_mapping' in 'encode_edge_size': categorical_mapping['admin'] must be a number
• encode_edge_weight: Invalid value for parameter 'categorical_mapping' in 'encode_edge_weight': categorical_mapping['admin'] must be a number
• encode_point_opacity: Invalid value for parameter 'categorical_mapping' in 'encode_point_opacity': categorical_mapping['admin'] must be a number
• encode_edge_opacity: Invalid value for parameter 'categorical_mapping' in 'encode_edge_opacity': categorical_mapping['admin'] must be a number
• encode_point_label: encode_point_label supports raw column binding only; categorical_mapping/default_mapping would create label/title complex encodings that Graphistry upload rejects
• encode_edge_label: encode_edge_label supports raw column binding only; categorical_mapping/default_mapping would create label/title complex encodings that Graphistry upload rejects
• encode_point_title: encode_point_title supports raw column binding only; categorical_mapping/default_mapping would create label/title complex encodings that Graphistry upload rejects
• encode_edge_title: encode_edge_title supports raw column binding only; categorical_mapping/default_mapping would create label/title complex encodings that Graphistry upload rejects
• apply_encodings({"encodePointLabel": ["role", {"admin": "Admin"}]}): React text binding payload supports only [column]; label/title categorical mappings are not supported

LOC Buckets

• Production: +389 / -53, net +336 LOC
• Tests: +227 / -0, net +227 LOC
• Changelog/schema artifacts: +12 / -3, net +9 LOC

Compatibility / Planner Surface

• Compiler-plan surface touched: no. This is public API, GFQL call validation/type parity, apply-encodings contract, and schema artifact work only.
• Public viz payload compatibility: this PR does not add label/title complex payload support because current Graphistry upload rejects Label/Title complex encoding names. The new label/title helpers bind raw columns only.
• React/component compatibility: audited /home/lmeyerov/Work/graphistry-js/projects/client-api-react/src/bindings.js; the React component exposes only the existing encodePointSize, point/edge color, axis, and point/edge icon props, so this PR does not add the new helpers to REACT_SETTING_NAMES / KnownReactSettingsDict. New keys are scoped to pygraphistry public helpers, GFQL call(), and apply_encodings() introspection.
• Frontend contract version: kept GRAPHISTRY_FRONTEND_CONTRACT_VERSION = 1; no server-facing or React component prop contract bump. The version-1 signature was refreshed for the compatible apply_encodings introspection key additions.
• Cross-lib consumer audit: these helpers are pygraphistry-surface parity, not a claim of end-to-end renderer parity for every target. Local findings are under plans/issue-1253-encode-parity/findings/:
  • encode_edge_size: upload accepts Size; pygraphistry serializes categorical mapping, but core viz has an edgeSize branch that does not currently consume mapping.categorical for edge size.
  • encode_edge_weight: upload accepts Weight; pygraphistry + forge ETL have edge-weight mapping paths, while core viz currently skips weight server-side interpretation.
  • encode_point_opacity / encode_edge_opacity: upload accepts Opacity; core viz treats opacity primarily as scalar settings and skips opacity server-side interpretation.
  • encode_point_label / encode_edge_label / encode_point_title / encode_edge_title: upload rejects Label/Title complex names, so this PR keeps these as raw column binding helpers and rejects mapping/default payloads.
• JSON Schema exporter/checker passes: python3 -m graphistry.devschemas.export --check.

Validation

• python3 -m pytest -q graphistry/tests/test_plotter.py -k "encode_parity or apply_encodings or label_complex" -> 11 passed, 66 deselected
• python3 -m pytest -q graphistry/tests/compute/test_call_operations.py -k "encode" -> 10 passed, 16 deselected
• python3 -m pytest -q graphistry/tests/test_dataset_id_invalidation.py -k "encoding_method_invalidates_dataset_id" -> 16 passed, 17 deselected
• python3 -m pytest -q graphistry/tests/compute/test_gfql_call_validation.py -k "encode_parity" -> 12 passed, 62 deselected
• python3 -m pytest -q graphistry/tests/test_schema_artifacts.py graphistry/tests/test_viz_settings.py graphistry/tests/test_validate_settings.py -> 28 passed
• python3 -m pytest -q graphistry/tests/ -k "encode" -> 87 passed, 6 skipped, 5053 deselected
• ./bin/ruff.sh [touched python files] -> passed
• ./bin/typecheck.sh [touched production python files] -> passed
• python3 -m graphistry.devschemas.export --check -> passed
• git diff --check origin/master -> passed
• Rebased onto origin/master @ 991c2dfcc44823e8cfeaf3d6653c7237e67a464e after master moved ahead; no conflicts.
• Review skill Waves 8-9 after current-master and CI verification -> converged, 0 BLOCKER/IMPORTANT findings before the DRY reduction.
• Review skill Waves 12-13 after py3.8 mypy fix -> converged, 0 BLOCKER/IMPORTANT findings.
• Review skill Waves 14-15 after final DRY alias cleanup -> converged, 0 BLOCKER/IMPORTANT findings.
• Reviewer follow-up validation for formatting, generic GFQL params, stable contract version, and client-api-react audit -> passed.
• Review skill Waves 18-19 after mapped-property rename and latest rebase -> converged, 0 BLOCKER/IMPORTANT findings.
• Second LOC reduction pass removed unnecessary facade type-alias re-exports and folded duplicate tests: +9 / -59, net -50 LOC vs the prior pushed head.
• Review skill Waves 20-21 after second LOC reduction and latest rebase -> converged, 0 BLOCKER/IMPORTANT findings.
• Full PR CI is green on rebased/reduced head 5c010060dd4a08584b37343a725522117eb3f1ba / run 26272586189, including changed-line coverage, schema artifacts, tck-gfql, full matrix, CodeQL, and Read the Docs.

DGX/RAPIDS not run: this touches public encode metadata/control-plane validation and schema artifacts, not DataFrame/cuDF/GPU execution paths.