refactor: Remove redundant Argument Access descriptions

Issue:
- 'Argument Access' section repeated 4 times (Line 593, 991, 1076, 1146)
- Full descriptions duplicated in each template
- ~15 lines of redundant content

Fix:
- Kept comprehensive description in Frontmatter Fields section (Line 593-596)
- Simplified in templates to single-line references
- Template 1: 3 lines → 1 line
- Template 2: 4 lines → 1 line
- Template 3: 3 lines → 1 line

After:
**Argument Access**: `$ARGUMENTS`, `$1`, `$2`, `$3` (see Frontmatter Fields above)

Impact:
- Removed 9 lines of redundancy
- Easier to maintain (single source of truth)
- Users still see relevant variables in templates

Author: NeilJo-GY

src/metaspec/templates/meta/sdd/commands/specify.md.j2

@@ -988,9 +988,7 @@ $ARGUMENTS
 
 You **MUST** consider the user input before proceeding (if not empty).
 
-**Argument Access**:
-- `$ARGUMENTS` - All arguments as single string
-- `$1`, `$2`, `$3` - Individual positional arguments
+**Argument Access**: `$ARGUMENTS`, `$1`, `$2`, `$3` (see [Frontmatter Fields](#frontmatter-fields-yaml-metadata) above)
 
 ## Purpose
 [What protocol-compliant output to produce]
@@ -1073,10 +1071,7 @@ $ARGUMENTS
 
 You **MUST** consider the user input before proceeding (if not empty).
 
-**Argument Access**:
-- `$ARGUMENTS` - All arguments as single string
-- `$1`, `$2`, `$3` - Individual positional arguments
-- `{ARGS}` - Escaped for script execution
+**Argument Access**: `$ARGUMENTS`, `$1`, `$2`, `$3`, `{ARGS}` (see [Frontmatter Fields](#frontmatter-fields-yaml-metadata) above)
 
 ## Purpose
 [What to produce, with script handling setup]
@@ -1148,9 +1143,7 @@ model: claude-3-5-haiku-20241022  # Can use lighter model for simple reminders
 $ARGUMENTS
 \```
 
-**Argument Access**:
-- `$1` - File to validate (if provided)
-- `$ARGUMENTS` - All arguments
+**Argument Access**: `$ARGUMENTS`, `$1` (see [Frontmatter Fields](#frontmatter-fields-yaml-metadata) above)
 
 ## Purpose
 Remind AI to suggest validation after producing content