feat(ui): instant match-score panel on the Candidate Fit tab

Adds a MatchScoreCard at the top of the Candidate Fit tab that loads the
deterministic /match-score endpoint independently of the slow AI
narrative, so users see a reproducible score, matched/missing keyword
chips, and per-section coverage immediately.

- MatchScore types + cached, attachment-independent load effect
- graceful 'not enough signal' state
- EN/NB translations
- frontend panel test (matched/missing/section + degraded state)
- backend integration tests for GetMatchScore (happy path + missing CV)
- README endpoint reference

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

job-tracker-ui/src/types.ts

@@ -132,6 +132,23 @@ export interface CandidateFitChannelGuidance {
   recruiterMessage: string[];
 }
 
+export interface MatchScoreSectionCoverage {
+  section: string;
+  matched: number;
+  total: number;
+}
+
+export interface MatchScore {
+  score: number;
+  band: string;
+  matchedCount: number;
+  totalKeywords: number;
+  matchedKeywords: string[];
+  missingKeywords: string[];
+  sectionCoverage: MatchScoreSectionCoverage[];
+  hasEnoughSignal: boolean;
+}
+
 export interface CandidateFit {
   matchSummary: string;
   fitLevel: string;