Adds render-layer regression coverage in packages/ai, where the #2702 fix lives. Asserts the anthropic dialect unwraps a single literal <thinking> envelope (no nesting), unwraps sibling envelopes independently (no malformed close/open boundary), and that a <thinking> envelope is not mistaken for the qwen3 <think> delimiter (prefix safety). The PR's existing test lives only in packages/coding-agent and cannot exercise the fix under the shared workspace node_modules symlink.
Addresses review feedback on #2702.
- Renamed ToolCallSyntax type to Dialect and Grammar interface to DialectDefinition across all packages.
- Moved grammar directory to dialect and updated all import paths in agent, ai, catalog, and coding-agent packages.
- Added renderTranscript and renderThinking methods to DialectDefinition, enabling native dialect-aware conversation serialization.
- Consolidated rendering utilities into new dialect/rendering.ts with shared helpers for ChatML, legacy text, and dialect-specific formatting.
- Updated conversation serialization in agent and coding-agent to use dialect.renderTranscript() for native turn envelope rendering.
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