feat: add admin publishing workflow and yar theme

Add Go/Postgres admin APIs, Angular admin UI, manual build flow, asset uploads, markdown import/export, configurable slug generation, and the Yar reading theme. Exclude local docs and generated development artifacts from version control.

frontend/admin/angular.json

@@ -0,0 +1,62 @@
+{
+  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
+  "version": 1,
+  "newProjectRoot": "projects",
+  "projects": {
+    "admin": {
+      "projectType": "application",
+      "schematics": {},
+      "root": "",
+      "sourceRoot": "src",
+      "prefix": "osaet",
+      "architect": {
+        "build": {
+          "builder": "@angular-devkit/build-angular:application",
+          "options": {
+            "outputPath": "dist/admin",
+            "index": "src/index.html",
+            "browser": "src/main.ts",
+            "polyfills": ["zone.js"],
+            "tsConfig": "tsconfig.app.json",
+            "assets": [],
+            "styles": ["src/styles.css"],
+            "scripts": []
+          },
+          "configurations": {
+            "production": {
+              "budgets": [
+                {
+                  "type": "initial",
+                  "maximumWarning": "500kB",
+                  "maximumError": "1MB"
+                }
+              ],
+              "outputHashing": "all"
+            },
+            "development": {
+              "optimization": false,
+              "extractLicenses": false,
+              "sourceMap": true
+            }
+          },
+          "defaultConfiguration": "production"
+        },
+        "serve": {
+          "builder": "@angular-devkit/build-angular:dev-server",
+          "configurations": {
+            "production": {
+              "buildTarget": "admin:build:production"
+            },
+            "development": {
+              "buildTarget": "admin:build:development"
+            }
+          },
+          "defaultConfiguration": "development"
+        }
+      }
+    }
+  },
+  "cli": {
+    "analytics": "1f777743-c088-4a64-b88c-12e453da36c1"
+  }
+}