Add feed summary preview and pinned interest filters

- Show a 6-line cross-source summary preview in each feed row.
- Pinned, mutually-exclusive filter pills: All, F1, Uganda, East Africa,
  South Africa, Finance, Tech. "All" is news-only (F1 lives only under F1);
  regions don't overlap (East Africa excludes Uganda & South Africa).
- Categorization correctness: regions match the headline only (the backend's
  summaries/outlets are polluted by over-clustering), and F1 takes precedence
  over every other pill since the backend mis-tags F1 as tech/finance/politics.
- Finance/Tech match the backend topic; sparse filters auto-pull more pages.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Jarvis/Views/Shared/Theme.swift

@@ -171,3 +171,69 @@ extension StorySummary {
         a.signalScore != b.signalScore ? a.signalScore > b.signalScore : a.id > b.id
     }
 }
+
+// MARK: - Pinned interest filters (client-side)
+//
+// The backend only classifies topics as finance/tech/politics/africa, so these
+// personal filters match keywords in the headline, summary, and source names of
+// the loaded stories instead of calling the API.
+
+struct Interest: Identifiable, Hashable {
+    let id: String
+    let label: String
+    var keywords: [String] = []
+    /// If any of these appear, the story is NOT this interest — used to keep the
+    /// region pills exclusive (East Africa excludes Uganda & South Africa).
+    var excludeKeywords: [String] = []
+    /// When set, matches the backend topic classification instead of keywords
+    /// (e.g. finance, tech).
+    var topicSlug: String? = nil
+    /// Whether to consider source/outlet names when matching. True only for F1
+    /// (its sources are the signal). Regions must NOT — an outlet's location is
+    /// not the story's location (e.g. a Congo story carried by an SA outlet).
+    var matchSources: Bool = false
+
+    func matches(_ s: StorySummary) -> Bool {
+        if let topicSlug {
+            return s.topic.caseInsensitiveCompare(topicSlug) == .orderedSame
+        }
+        // Headline only — the backend's summaries are polluted by over-clustering
+        // (a Congo headline can carry a South-Africa summary), so they're unsafe
+        // to match on. F1 additionally trusts its (clean) source names.
+        var hay = s.headline
+        if matchSources { hay += " " + s.sources.map(\.name).joined(separator: " ") }
+        hay = hay.lowercased()
+        if excludeKeywords.contains(where: { hay.contains($0) }) { return false }
+        return keywords.contains { hay.contains($0) }
+    }
+
+    // Region keywords are place/person names found in the story text — never
+    // outlet names (which are unreliable due to backend over-clustering).
+    private static let ugandaKeywords = ["uganda", "ugandan", "kampala", "museveni",
+                                         "entebbe", "jinja", "gulu"]
+    private static let southAfricaKeywords = ["south africa", "south african", "johannesburg",
+                                              "cape town", "pretoria", "durban", "ramaphosa",
+                                              "eskom", "gauteng", "western cape", "soweto",
+                                              "drakensberg", "mbalula", "zuma"]
+
+    static let f1 = Interest(id: "f1", label: "F1",
+        keywords: ["formula 1", "formula one", "grand prix", "f1", "verstappen", "hamilton",
+                   "mclaren", "ferrari", "red bull", "racefans", "motorsport", "autosport",
+                   "pole position", "pirelli", "qualifying", "fia", "planetf1"],
+        matchSources: true)
+
+    /// Pinned filter pills, in order. Regions are mutually exclusive.
+    static let pinned: [Interest] = [
+        f1,
+        Interest(id: "uganda", label: "Uganda", keywords: ugandaKeywords),
+        Interest(id: "east-africa", label: "East Africa",
+                 keywords: ["east africa", "eastafrican", "kenya", "kenyan", "nairobi",
+                            "tanzania", "tanzanian", "dar es salaam", "rwanda", "rwandan",
+                            "kigali", "ethiopia", "ethiopian", "addis ababa", "burundi",
+                            "south sudan", "juba"],
+                 excludeKeywords: ugandaKeywords + southAfricaKeywords),
+        Interest(id: "south-africa", label: "South Africa", keywords: southAfricaKeywords),
+        Interest(id: "finance", label: "Finance", topicSlug: "finance"),
+        Interest(id: "tech", label: "Tech", topicSlug: "tech"),
+    ]
+}