feat: add Microsoft Access driver with ODBC support and update skill references

[Esteban040404]

Summary

• Add AccessDriver implementing the full IDatabaseDriver interface via the odbc npm package
• Register "access" as a supported engine in factory.ts (SupportedDbType)
• Update SKILL.md to reflect all four supported engines (PostgreSQL, MySQL, SQLite, Access) including a feature support matrix
• Add engine-specific reference files: mysql.md, sqlite.md, access.md
• Expand tools-reference.md with per-engine behavior notes for schema param, alterTable, createView, dropIndex, and
  createTrigger

Technical Notes

Driver (src/drivers/access.ts)

• Uses the odbc package (ODBC bridge); Windows-only at runtime — requires the Microsoft Access Database Engine 2016
  Redistributable or an Office installation
• Accepts a file path (.accdb / .mdb) and auto-constructs the ODBC connection string: Driver={Microsoft Access Driver (*.mdb, *.accdb)};DBQ=<path>; also accepts full ODBC strings or DSN names
• Identifier quoting uses square brackets [name] (JET SQL convention)
• listIndexes / dropIndex use statistics() via a typed runtime cast — the odbc package does not expose this catalog method
  in its TypeScript definitions, but the underlying ODBC driver supports it; the call is wrapped in try/catch per table
• dropIndex searches all tables to find the owning table (required by JET's DROP INDEX [name] ON [table] syntax)
• createView / dropView silently drop before recreating — JET SQL has no CREATE OR REPLACE VIEW
• dropTable is wrapped in try/catch (JET has no DROP TABLE IF EXISTS)
• Unsupported features throw descriptive errors: schemas, triggers, functions, extensions, sequences, roles/grants
  (Access workgroup security is deprecated in .accdb)
• renameTo in alterTable throws — JET SQL has no RENAME TABLE; workaround documented in access.md
• Soft delete must be handled at the application layer (no SQL triggers in Access)

Skill updates

• SKILL.md description and engine notes updated; added Engine Support Matrix table and connection string examples per engine
• tools-reference.md now documents how the schema parameter maps per engine and per-engine behavior differences for key tools
• mysql.md, sqlite.md, access.md are new reference files following the same structure as postgres.md