Initialize blog scaffold

Add the CLI, site, and sample content so the project can run locally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/internal/cli/sqlite_schema.sql

@@ -0,0 +1,35 @@
+CREATE TABLE IF NOT EXISTS posts (
+    id TEXT PRIMARY KEY,
+    slug TEXT NOT NULL UNIQUE,
+    title TEXT NOT NULL,
+    summary TEXT NOT NULL DEFAULT '',
+    content_markdown TEXT NOT NULL DEFAULT '',
+    status TEXT NOT NULL DEFAULT 'draft',
+    tags_json TEXT NOT NULL DEFAULT '[]',
+    cover TEXT NOT NULL DEFAULT '',
+    file_path TEXT NOT NULL DEFAULT '',
+    version INTEGER NOT NULL DEFAULT 1,
+    content_hash TEXT NOT NULL DEFAULT '',
+    slug_source TEXT NOT NULL DEFAULT 'manual',
+    slug_locked INTEGER NOT NULL DEFAULT 0,
+    published_at TEXT,
+    created_at TEXT NOT NULL,
+    updated_at TEXT NOT NULL,
+    deleted_at TEXT
+);
+
+CREATE INDEX IF NOT EXISTS idx_posts_status ON posts(status);
+CREATE INDEX IF NOT EXISTS idx_posts_published_at ON posts(published_at);
+
+CREATE TABLE IF NOT EXISTS settings (
+    key TEXT PRIMARY KEY,
+    value_json TEXT NOT NULL,
+    version INTEGER NOT NULL DEFAULT 1,
+    updated_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS sync_state (
+    key TEXT PRIMARY KEY,
+    value TEXT NOT NULL,
+    updated_at TEXT NOT NULL
+);