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/FetchPageResponse.cs

@@ -0,0 +1,25 @@
+namespace PageFetcher.Models;
+
+/// <summary>
+/// Result of a page fetch operation.
+/// </summary>
+public sealed class FetchPageResponse
+{
+    /// <summary>Final URL after any redirects.</summary>
+    public string Url { get; set; } = string.Empty;
+
+    /// <summary>HTTP status code returned by the page. <c>0</c> on network failure.</summary>
+    public int StatusCode { get; set; }
+
+    /// <summary>Full rendered HTML as returned by Playwright.</summary>
+    public string Html { get; set; } = string.Empty;
+
+    /// <summary>Plain text extracted from the HTML (script/style stripped, whitespace normalised).</summary>
+    public string Text { get; set; } = string.Empty;
+
+    /// <summary>Whether the fetch succeeded. <c>false</c> on timeout or network error.</summary>
+    public bool Success { get; set; }
+
+    /// <summary>Exception message when <see cref="Success"/> is <c>false</c>.</summary>
+    public string? Error { get; set; }
+}