Initial documentation for Vertica.

[mikependon]

Summary

Adds end-to-end documentation for RepoDB's Vertica support: RepoDb.Vertica (core provider) and RepoDb.Vertica.BulkOperations (bulk operations extension), following the same structure and conventions already established for the other providers (Db2, Firebird, Oracle, etc.).

• Get Started — installation (including the process-wide CultureInfo.InvariantCulture caveat UseVertica() applies), table/model setup, and every CRUD operation with Vertica-specific behavior and gotchas.
• Attributes — VerticaType, SourceColumn, SourceColumnNullMapping, SourceVersion (decorating VerticaParameter).
• Classes — VerticaBootstrap, VerticaConfiguration, VerticaDbSetting, VerticaDbHelper, VerticaStatementBuilder, three resolvers (VerticaConvertFieldResolver, DbTypeToVerticaStringNameResolver, VerticaDbTypeNameToClientTypeResolver, DbTypeNameToColumnNameResolver), the TimeToDateTimePropertyHandler property handler, and the bulk package's VerticaBulkInsertMapItem / VerticaTraceKeys. (VerticaBulkCopy is internal and intentionally has no page.)
• Enumerations — VerticaBulkImportIdentityBehavior, VerticaBulkImportPseudoTableType.
• Operations — a provider index page (mechanics, pseudo-table types, generated SQL shapes) plus BulkInsert, BulkMerge, BulkUpdate, BulkDelete, BulkDeleteByKey, each with a Mermaid call-flow diagram.
• Releases — release/vertica and release/verticabulk, each with a "Known limitations" section.
• Site wiring — registered the new Get Started and Release pages in _data/documentation.yml's search index, added Vertica to the database picker on home.md, and to the "Supported Providers" list in features/bulkoperations.md.

No existing pages for other providers were changed beyond those three registration edits.

Notable findings surfaced as "Known limitations" rather than assumed to work

Documentation was written directly from the RepoDb.Vertica/RepoDb.Vertica.BulkOperations source, and a few things worth a second look before this ships as real (non-preview) behavior:

1. Core Merge/MergeAll may violate Vertica's own compound-statement restriction. VerticaStatementBuilder compiles Merge/MergeAll as a single UPDATE ...; INSERT ... command text, with parameters in both halves. Elsewhere in the same codebase, IsInsertAllBatchable's own remarks state that VerticaCommand "refuses to execute [a compound stmt1; stmt2 statement] once it carries a parameter." These two facts appear to contradict each other. Flagged prominently in release/vertica, class/vertica/verticastatementbuilder, operation/vertica, and the Get Started page.
2. GetScopeIdentity/GetScopeIdentityAsync run SELECT LAST_INSERT_ID(), and the bulk package's identity read-back arithmetic (subtracting a descending offset from that one value) assumes Vertica assigns IDENTITY/AUTO_INCREMENT values strictly contiguously in insertion order. Neither has been checked against a live instance.
3. Duplicate property handler. RepoDb.PropertyHandlers.VerticaTimeToDateTimePropertyHandler and RepoDb.PropertyHandlers.Vertica.TimeToDateTimePropertyHandler are near-identical; only the latter is referenced by the library's own integration tests. Documented only the one actually in use, and called out the other as likely dead code from a refactor.

Test plan

This is a documentation-only change (Jekyll pages + YAML data, no application code).

• bundle exec jekyll build (or equivalent) completes without broken front matter / liquid errors.
• Spot-check the new pages render correctly and the sidebar nav picks up the new "Vertica" sections under GET STARTED, ATTRIBUTES, CLASSES, ENUMERATIONS, OPERATIONS, and RELEASES.
• Click through cross-links between the new Vertica pages (Get Started ↔ Operations ↔ Enumerations ↔ Classes ↔ Releases) to confirm no dead links.
• Confirm the home page's database list and the Bulk Operations feature page show the new "Vertica" entries.
• Have the two flagged correctness concerns above (compound Merge statement, LAST_INSERT_ID() assumptions) verified against a live Vertica instance, ideally before or alongside promoting the underlying RepoDb.Vertica/RepoDb.Vertica.BulkOperations packages out of preview.