fix(antelope): ABI safety, table evidence, indexed lookups, arbitrary layouts, viz

[j76823284-hash]

Summary

Correctness + scalability pass on the Antelope contract support ahead of merge.

• ABI object/version validation (crash fix). .abi files are now routed to a dedicated antelope_abi parser that validates the top-level is a JSON object before any .get(). A JSON array (the Solidity/Ethereum ABI shape) previously reached .get() and crashed parsing; it is now skipped safely. Non-string version, plain JSON objects, and malformed JSON are all skipped without producing nodes.
• Tightened table evidence. table_schema is now tagged only on a real TABLE macro declaration in the same file (tree-sitter parses TABLE account {...} as a function named TABLE). Ordinary helper methods (primary_key/by_*) on plain C++ objects no longer become phantom tables.
• Indexed graph queries (no full-graph scan). Dead-code detection no longer rescans the filesystem per node. _antelope_is_runtime_symbol(store, node) reads the antelope_kind tag already stored in the DB — O(1) per node, scales to large repos.
• Arbitrary contract layouts. Dropped the hard /contracts/ path requirement; contracts are detected by positive runtime signals (ACTION/TABLE/multi_index/on_notify) anywhere in the tree.
• Visualization includes dapp action edges + antelope surfaces. Added CALLS_ACTION (color, dashed style, arrow marker, legend) and dedicated Action/Table/Contract node kinds to both D3 templates.
• Whitelist metadata, don't dump every extra field. node_to_dict/edge_to_dict now emit only a curated subset (antelope_kind, antelope_runtime, antelope_version, abi_action, abi_table, notebook_format, message_type for nodes; antelope, runtime for edges), preventing large internal payloads from leaking into the exported graph.

Test plan

• 16 new unit tests (ABI parsing safety, table evidence, layout independence, indexed dead-code lookup, metadata whitelist) — all passing.
• Full suite: 1977 passed, 0 failed, 79.25% coverage (≥65% required). Ruff clean on all changed source files.
• mypy and bandit run in CI (not installed in the local venv, so not executed here).

Notes

• Includes the original "model Antelope contract runtime surfaces" feature commit (894ef8c) rebased onto current origin/main (resolved conflicts in parser.py, graph.py, and the test files).
• One rebase-regression fix is folded in: the bare-endpoint resolver's CALLS_ACTION handling now selects the kind column for all edge kinds.