feat: add page-fetcher-api — centralised Playwright page fetcher

Introduces page-fetcher-api, a new internal ASP.NET Core service that
centralises all web-page fetching through a single Playwright (headless
Chromium) browser instance. All fetches are persisted to the pageFetcher
SQL schema for auditing.

New projects:
- Apis/page-fetcher-api-models: FetchPageRequest, FetchPageResponse, IPageFetcherApiClient
- Apis/page-fetcher-data: PageFetchDbContext, PageFetchEntity, InitialSchema migration (schema: pageFetcher)
- Apis/page-fetcher-api: PlaywrightBrowserService (singleton), PageFetcherService, PageController

Changes to existing services:
- cv-matcher-api: JobTextExtractor now calls IPageFetcherApiClient instead of HttpClient
- cv-search-job: HtmlJobSearcher uses IPageFetcherApiClient (removes inline Playwright);
  CvSearchJobTask fetches individual job pages and applies keyword pre-filter before
  LLM call; passes pre-fetched JobDescription to cv-matcher-api to skip re-fetch
- common: add PageFetcherApiSettings
- docker-compose.yml, build.yml: add new service + env vars for callers

Closes #43

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

Apis/page-fetcher-api-models/IPageFetcherApiClient.cs

@@ -0,0 +1,16 @@
+using Refit;
+
+namespace PageFetcher.Models;
+
+/// <summary>
+/// Refit client for the internal page-fetcher-api service.
+/// All calls require the <c>X-Internal-Api-Key</c> header, configured at registration time.
+/// </summary>
+public interface IPageFetcherApiClient
+{
+    /// <summary>
+    /// Fetches a web page via headless Chromium and returns the rendered HTML and extracted plain text.
+    /// </summary>
+    [Post("/api/page/fetch")]
+    Task<FetchPageResponse> FetchAsync([Body] FetchPageRequest request, CancellationToken ct = default);
+}