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/repositories/sqlite.py

@@ -30,6 +30,7 @@ CREATE TABLE IF NOT EXISTS prompt_artifacts (
     artifact_type TEXT NOT NULL,
     content_digest TEXT NOT NULL,
     content_size INTEGER DEFAULT 0,
+    content TEXT DEFAULT '',
     metadata JSON,
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
@@ -59,6 +60,13 @@ def initialize_artifact_tables(db_path: str) -> None:
     conn = sqlite3.connect(db_path)
     try:
         conn.executescript(ARTIFACT_TABLES_SQL)
+        # Migration: add content column to existing databases
+        try:
+            conn.execute(
+                "ALTER TABLE prompt_artifacts ADD COLUMN content TEXT DEFAULT ''"
+            )
+        except sqlite3.OperationalError:
+            pass  # Column already exists
         conn.commit()
     finally:
         conn.close()
@@ -107,8 +115,8 @@ class SQLiteArtifactRepository(IArtifactRepository):
                 """
                 INSERT INTO prompt_artifacts (
                     id, space_id, name, artifact_type, content_digest,
-                    content_size, metadata, created_at, updated_at
-                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+                    content_size, content, metadata, created_at, updated_at
+                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
                 """,
                 (
                     artifact.id,
@@ -117,6 +125,7 @@ class SQLiteArtifactRepository(IArtifactRepository):
                     artifact.artifact_type.value,
                     artifact.content_digest,
                     artifact.content_size,
+                    artifact.content,
                     json.dumps(artifact.metadata.to_dict()),
                     artifact.created_at.isoformat(),
                     artifact.updated_at.isoformat(),
@@ -251,12 +260,14 @@ class SQLiteArtifactRepository(IArtifactRepository):
             cursor = conn.execute(
                 """
                 UPDATE prompt_artifacts
-                SET content_digest = ?, content_size = ?, metadata = ?, updated_at = ?
+                SET content_digest = ?, content_size = ?, content = ?,
+                    metadata = ?, updated_at = ?
                 WHERE id = ?
                 """,
                 (
                     artifact.content_digest,
                     artifact.content_size,
+                    artifact.content,
                     json.dumps(artifact.metadata.to_dict()),
                     artifact.updated_at.isoformat(),
                     artifact.id,
@@ -326,6 +337,7 @@ class SQLiteArtifactRepository(IArtifactRepository):
             artifact_type=ArtifactType(row["artifact_type"]),
             content_digest=row["content_digest"],
             content_size=row["content_size"],
+            content=row["content"] or "",
             metadata=ArtifactMetadata.from_dict(metadata_dict),
             created_at=datetime.fromisoformat(row["created_at"]),
             updated_at=datetime.fromisoformat(row["updated_at"]),