feat(dbml): @postgres/@sqlite dialect directives (#19)

Add parseable `@<namespace>[(<target>)]: <args>` directives embedded in DBML.
They are stored losslessly on each object's Metadata, round-trip unchanged
through the DBML writer, and are translated to SQL only by the writer for the
matching dialect.

- models: Directive type + catalog; Metadata map added to Column and Index
- dbml reader: parse and attach directives at database/table/column/index
  level; line-numbered errors; repeatable by default with singleton duplicate
  detection. Fixes a preexisting bug where an `indexes {}` closing brace ended
  the table early, dropping trailing Note: and directive lines.
- dbml writer: re-emit directives at their location; idempotent output
- pgsql writer: PARTITION BY / INHERITS / WITH / TABLESPACE (table),
  STORAGE / COMPRESSION / identity (column), WITH / TABLESPACE (index)
- sqlite writer: WITHOUT ROWID / STRICT (table), COLLATE (column)
- --strict-directives flag on ReaderOptions and WriterOptions
- docs/DBML_DIRECTIVES.md + reader/writer READMEs

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ss2MY5J11cRGwEz86ZXk7d

pkg/writers/sqlite/templates.go

@@ -40,11 +40,12 @@ func NewTemplateExecutor(opts *writers.WriterOptions) (*TemplateExecutor, error)
 
 // TableTemplateData contains data for table template
 type TableTemplateData struct {
-	Schema      string
-	Name        string
-	Columns     []*models.Column
-	PrimaryKey  *models.Constraint
-	ForeignKeys []ForeignKeyTemplateData
+	Schema       string
+	Name         string
+	Columns      []*models.Column
+	PrimaryKey   *models.Constraint
+	ForeignKeys  []ForeignKeyTemplateData
+	TableOptions string
 }
 
 // ForeignKeyTemplateData contains data for an inline FOREIGN KEY clause
@@ -188,11 +189,12 @@ func BuildTableTemplateData(schema string, table *models.Table) TableTemplateDat
 	}
 
 	return TableTemplateData{
-		Schema:      schema,
-		Name:        table.Name,
-		Columns:     columns,
-		PrimaryKey:  pk,
-		ForeignKeys: fks,
+		Schema:       schema,
+		Name:         table.Name,
+		Columns:      columns,
+		PrimaryKey:   pk,
+		ForeignKeys:  fks,
+		TableOptions: sqliteTableOptions(table),
 	}
 }