Improve MSSQL analysis and diagnostic exports

[dvasdekis]

Summary

Promote the completed pre_66 stack into pondpilot/flowscope:master.

This PR consolidates the investigation-driven fixes for the MSSQL/Synapse corpus and preserves diagnostic metadata across the core, CLI, WASM, and report-export boundaries.

Changes

MSSQL and SQL analysis

• Handle trailing, repeated, case-insensitive, and CRLF MSSQL GO batch separators.
• Preserve statement ranges and WASM analysis/statement-splitting behavior around GO.
• Track parsed QUALIFY predicates as structured QUALIFY filters.
• Preserve source references from parsed OPENJSON and XMLTABLE table factors in the legacy extractor.

Diagnostics and metadata

• Normalize multi-file lint statement indices to the global AnalyzeResult statement identity.
• Attach source names to lint and statement-scoped issues.
• Preserve structured lint metadata and autofix data in CLI JSON output.
• Synchronize the API schema, generated TypeScript types, and issue documentation.

WASM and exports

• Fix the WASM export request boundary to deserialize the TypeScript projectName and exportedAt fields.
• Add native regression coverage for the WASM export payload contract.
• Preserve source, statement, span, lint provenance, and autofix metadata in HTML and CSV exports.
• Add an Issues worksheet to XLSX exports while preserving existing worksheet names and order.
• Add escaping and serialization regressions for rich issue data.

Deliberate scope boundaries

• Standard Synapse OPENROWSET grammar is not claimed here; sqlparser still needs dedicated upstream grammar/AST support for the documented forms.
• No new public synapse dialect is introduced; Synapse-compatible syntax remains under the existing MSSQL dialect.
• Full PIVOT/UNPIVOT generated-column semantics, dynamic EXECUTE lineage, and complete external-rowset schema inference remain follow-up work.

Validation

Focused validation completed during the stack:

• cargo fmt --all
• cargo test --locked -p flowscope-core --test schema_guard api_schema_snapshot_matches -- --nocapture
• cargo test --locked -p flowscope-core --test lineage_engine snowflake_qualify_clause_filters_window_results -- --nocapture
• cargo test --locked -p flowscope-core --test lineage_engine openjson_table_factor_sql_server -- --nocapture
• cargo test --locked -p flowscope-core --lib extractors::tests -- --nocapture
• cargo test --locked -p flowscope-export --test export_formats --no-default-features
• cargo test --locked -p flowscope-wasm --test analysis -- --nocapture

The browser WASM harness was added but not run in the development container because Chromium/wasm-pack were unavailable. CI should run the normal workspace checks before merge.

Fixes #68

[dvasdekis]

oops, sorry, not yet ready