fix(prompts): fix three infrastructure bugs in prompt dependency resolution

- ContentMacro: add __post_init__ to auto-derive raw_text when built
  programmatically, preventing str.replace("", X) corruption
- MacroParser: add @{target} shorthand syntax support mapped to REQUIRED kind,
  updating parse, has_macros, count_macros, and find_macro_positions
- Artifact: store content in model and SQLite DB, replace resolver placeholder
  with actual artifact content, add migration for existing databases

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

markitect/prompts/templates/parser.py

@@ -38,6 +38,9 @@ class MacroParser:
         re.IGNORECASE
     )
 
+    # Shorthand pattern: @{target} — maps to MacroKind.REQUIRED
+    SHORTHAND_PATTERN = re.compile(r'@\{([^}]+)\}')
+
     # Parameter pattern: |key=value
     PARAM_PATTERN = re.compile(r'\|([^=]+)=([^|]+)')
 
@@ -95,6 +98,19 @@ class MacroParser:
                     f"Line {line_number}: {e}"
                 ) from e
 
+        # Scan for @{target} shorthand syntax
+        for match in self.SHORTHAND_PATTERN.finditer(line):
+            target = match.group(1).strip()
+            raw_text = match.group(0)
+            if target:
+                macros.append(ContentMacro(
+                    kind=MacroKind.REQUIRED,
+                    target=target,
+                    parameters={},
+                    raw_text=raw_text,
+                    line_number=line_number,
+                ))
+
         return macros
 
     def _parse_match(self, match: re.Match, line_number: int) -> ContentMacro:
@@ -172,7 +188,7 @@ class MacroParser:
             content: Template content
 
         Returns:
-            List of (start_pos, end_pos, macro_text) tuples
+            List of (start_pos, end_pos, macro_text) tuples sorted by position
         """
         positions = []
         for match in self.MACRO_PATTERN.finditer(content):
@@ -181,6 +197,13 @@ class MacroParser:
                 match.end(),
                 match.group(0)
             ))
+        for match in self.SHORTHAND_PATTERN.finditer(content):
+            positions.append((
+                match.start(),
+                match.end(),
+                match.group(0)
+            ))
+        positions.sort(key=lambda p: p[0])
         return positions
 
     def count_macros(self, content: str) -> dict:
@@ -211,4 +234,4 @@ class MacroParser:
         Returns:
             True if any macros found
         """
-        return bool(self.MACRO_PATTERN.search(content))
+        return bool(self.MACRO_PATTERN.search(content) or self.SHORTHAND_PATTERN.search(content))