fix: allow keyword module names in DESCRIBE MODULE

Adding AGENT, AGENTS, KNOWLEDGE, BASES, CONSUMED, MCP as lexer tokens
shadowed module names matching those keywords — e.g. a module literally
called "Agents" could no longer be parsed by DESCRIBE MODULE Agents
because the rule required a bare IDENTIFIER and "Agents" now lexes as
the AGENTS keyword.

Fix: DESCRIBE MODULE now accepts identifierOrKeyword (the same helper
rule qualifiedName uses), which matches both IDENTIFIER and any reserved
keyword. The visitor reads via ctx.IdentifierOrKeyword() with a fallback
to ctx.IDENTIFIER() for safety.

Verified:
- DESCRIBE MODULE Agents now works
- DESCRIBE MODULE Agents WITH ALL now works
- DESCRIBE MODULE WeatherDemo still works (non-keyword module)
- LIST AGENTS IN Agents still works (qualifiedName path was already OK)

Note: LIST MODULES Agents is not supported — LIST MODULES takes no
filter. Users looking at a single module's contents should use
DESCRIBE MODULE <name> WITH ALL or LIST <type> IN <module>.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

mdl/grammar/MDLParser.g4

@@ -3038,7 +3038,7 @@ describeStatement
     | DESCRIBE CONSTANT qualifiedName
     | DESCRIBE JAVA ACTION qualifiedName
     | DESCRIBE JAVASCRIPT ACTION qualifiedName
-    | DESCRIBE MODULE IDENTIFIER (WITH ALL)?  // DESCRIBE MODULE Name [WITH ALL] - optionally include all objects
+    | DESCRIBE MODULE identifierOrKeyword (WITH ALL)?  // DESCRIBE MODULE Name [WITH ALL] - optionally include all objects
     | DESCRIBE MODULE ROLE qualifiedName        // DESCRIBE MODULE ROLE Module.RoleName
     | DESCRIBE USER ROLE STRING_LITERAL          // DESCRIBE USER ROLE 'Administrator'
     | DESCRIBE DEMO USER STRING_LITERAL          // DESCRIBE DEMO USER 'demo_admin'

mdl/grammar/parser/MDLParser.interp

@@ -668,10 +668,14 @@ func (b *Builder) ExitDescribeStatement(ctx *parser.DescribeStatementContext) {
 		return
 	}
 
-	// Handle DESCRIBE MODULE specially (uses IDENTIFIER not qualifiedName)
+	// Handle DESCRIBE MODULE specially (uses identifierOrKeyword — accepts
+	// module names that happen to match a keyword, like "Agents").
 	if ctx.MODULE() != nil {
 		var moduleName string
-		if id := ctx.IDENTIFIER(); id != nil {
+		if iok := ctx.IdentifierOrKeyword(); iok != nil {
+			moduleName = iok.GetText()
+		} else if id := ctx.IDENTIFIER(); id != nil {
+			// Fallback for older grammar versions.
 			moduleName = id.GetText()
 		}
 		b.statements = append(b.statements, &ast.DescribeStmt{