M9 #4.6 (pass-2): Dashboard Overview/Sessions split + chat project bar

Pass-2 feedback bundled into one architectural commit:

1. **Project indicator moved out of the nav-bar principal slot.** The
   iPhone nav bar's .principal area gets squeezed to icon-only when
   adjacent toolbar buttons exist — the result was a folder icon with
   no project-name text, which is worse than no indicator at all. New
   `projectContextBar` renders a full-width tinted strip BELOW the
   nav bar when a session is project-attributed: "Project chat"
   caption + folder icon + full project name. Scrolls away with the
   message list. Pattern cribbed from Slack's channel-topic header
   and Apple Mail's sender strip.

2. **Dashboard split into Overview + Sessions sub-tabs.** Segmented
   picker at the top. Overview = stats + 5 most-recent sessions for
   at-a-glance; Sessions = the deeper 25-session list with a project
   filter. `See all` button on Overview's Recent Sessions header
   switches tabs. Addresses pass-2 complaint: "The dashboard might
   need tabs to break it down better."

3. **Project filter on the Sessions sub-tab.** Menu picker (scales
   to N projects; segmented doesn't). "All projects" clears; each
   project entry filters to sessions attributed there. Uses the same
   attribution map loaded once in `IOSDashboardViewModel.load()`, so
   filtering is an O(n) in-memory pass over 25 sessions — no extra
   SFTP traffic. Addresses pass-2 complaint: "we should add a filter
   to the sessions selector in the dash to see by project."

4. **`IOSDashboardViewModel` exposes the wider surface:**
   - `allSessions` (25-session window, feeds the Sessions tab)
   - `allProjects` (project registry, drives the filter menu)
   - `sessions(filteredBy: String?)` helper — accepts a project name
     (nil = all), returns filtered subset.

Mac parity note from the earlier commit message still stands — Mac's
global Sessions list doesn't currently filter by project either.
That's a parallel post-TestFlight followup.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scarf/Packages/ScarfIOS/Sources/ScarfIOS/IOSDashboardViewModel.swift

@@ -28,7 +28,12 @@ public final class IOSDashboardViewModel {
     // MARK: - Published state
 
     public var stats: HermesDataService.SessionStats = .empty
+    /// Recent 5 sessions for the Overview sub-tab (glance-only surface).
     public var recentSessions: [HermesSession] = []
+    /// Deeper session list for the Sessions sub-tab — larger window +
+    /// filterable by project. Default 25; enough to cover "what did I
+    /// work on this week" without paging.
+    public var allSessions: [HermesSession] = []
     public var sessionPreviews: [String: String] = [:]
     public var isLoading: Bool = true
 
@@ -39,6 +44,10 @@ public final class IOSDashboardViewModel {
     /// sessions on screen are attributed.
     public private(set) var sessionProjectNames: [String: String] = [:]
 
+    /// Every configured project, for the filter picker in the
+    /// Sessions sub-tab. Populated alongside `sessionProjectNames`.
+    public private(set) var allProjects: [ProjectEntry] = []
+
     /// Surfaced when the SQLite snapshot or DB open fails. Shown in a
     /// yellow banner above the stats with a "Retry" button. `nil` means
     /// the last load was healthy.
@@ -63,7 +72,8 @@ public final class IOSDashboardViewModel {
 
         stats = await dataService.fetchStats()
         recentSessions = await dataService.fetchSessions(limit: 5)
-        sessionPreviews = await dataService.fetchSessionPreviews(limit: 5)
+        allSessions = await dataService.fetchSessions(limit: 25)
+        sessionPreviews = await dataService.fetchSessionPreviews(limit: 25)
 
         // Attribution lookup (pass-2 UX): load the session→project
         // sidecar + project registry once so Dashboard rows can show
@@ -72,7 +82,7 @@ public final class IOSDashboardViewModel {
         // cell. Failure is silent — the absence of project labels is
         // a cosmetic degradation, not a data-loss problem.
         let ctx = context
-        let attributions: [String: String] = await Task.detached {
+        let bundle: (names: [String: String], projects: [ProjectEntry]) = await Task.detached {
             let attribution = SessionAttributionService(context: ctx)
             let projectRegistry = ProjectDashboardService(context: ctx).loadRegistry()
             let pathToName = Dictionary(
@@ -85,14 +95,28 @@ public final class IOSDashboardViewModel {
                     result[sessionID] = name
                 }
             }
-            return result
+            return (names: result, projects: projectRegistry.projects)
         }.value
-        sessionProjectNames = attributions
+        sessionProjectNames = bundle.names
+        allProjects = bundle.projects
 
         await dataService.close()
         isLoading = false
     }
 
+    /// Sessions matching the given project filter. `nil` returns
+    /// all 25 recent sessions (no filtering). `projectName` is the
+    /// ProjectEntry.name that's the key in `sessionProjectNames`, so
+    /// the filter is an O(n) dict lookup per session — cheap at our
+    /// 25-session window. Sorting is preserved (newest first) from
+    /// the upstream `fetchSessions(limit:)` query.
+    public func sessions(filteredBy projectName: String?) -> [HermesSession] {
+        guard let projectName, !projectName.isEmpty else { return allSessions }
+        return allSessions.filter { session in
+            sessionProjectNames[session.id] == projectName
+        }
+    }
+
     /// Helper used by DashboardView rows. Returns the project display
     /// name a session is attributed to, or nil for unattributed
     /// sessions (CLI-started, or started before v2.3).