feat: inline unsubscribe button on email rows

- ✉✕ button appears on rows where the email has a List-Unsubscribe header
- One-click POST / HTTP GET executed automatically; shows ✓ on success
- mailto: targets open the user mail client (we never auto-send email)
- POST /email/{id}/unsubscribe: detects sender, then processes — UserId scoped
- EmailSummaryDto gains IsStarred, HasListUnsubscribe, SupportsOneClick fields
- Both SearchService and CleanupService updated to populate new DTO fields

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

src/InboxIntel.Api/Controllers/EmailController.cs

@@ -1,7 +1,9 @@
 using InboxIntel.Application.Abstractions;
 using InboxIntel.Application.DTOs;
 using InboxIntel.Domain.Enums;
+using InboxIntel.Infrastructure.Persistence;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 
 namespace InboxIntel.Api.Controllers;
 
@@ -15,7 +17,15 @@ namespace InboxIntel.Api.Controllers;
 public class EmailController : ApiControllerBase
 {
     private readonly ICleanupService _cleanup;
-    public EmailController(ICleanupService cleanup) => _cleanup = cleanup;
+    private readonly IUnsubscribeService _unsub;
+    private readonly AppDbContext _db;
+
+    public EmailController(ICleanupService cleanup, IUnsubscribeService unsub, AppDbContext db)
+    {
+        _cleanup = cleanup;
+        _unsub = unsub;
+        _db = db;
+    }
 
     [HttpPost("{id:guid}/read")]
     public Task<IActionResult> MarkRead(Guid id, CancellationToken ct) => Act(id, CleanupActionType.MarkRead, ct);
@@ -35,6 +45,32 @@ public class EmailController : ApiControllerBase
     [HttpPost("{id:guid}/untrash")]
     public Task<IActionResult> Untrash(Guid id, CancellationToken ct) => Act(id, CleanupActionType.Archive, ct);
 
+    /// <summary>
+    /// Inline unsubscribe. Detects the unsubscribe mechanism for the email's sender,
+    /// then executes it (HTTP one-click or HTTP link). mailto targets cannot be sent
+    /// automatically — the mailto URI is returned so the user can action it themselves.
+    /// </summary>
+    [HttpPost("{id:guid}/unsubscribe")]
+    public async Task<IActionResult> Unsubscribe(Guid id, CancellationToken ct)
+    {
+        var email = await _db.Emails.FirstOrDefaultAsync(e => e.Id == id && e.UserId == UserId, ct);
+        if (email is null) return NotFound();
+        if (!email.HasListUnsubscribe) return BadRequest(new { error = "Email has no List-Unsubscribe header." });
+
+        await _unsub.DetectAsync(UserId, ct);
+
+        var item = await _db.UnsubscribeItems
+            .FirstOrDefaultAsync(u => u.UserId == UserId && u.SenderId == email.SenderId, ct);
+        if (item is null) return BadRequest(new { error = "No unsubscribe target found." });
+
+        if (item.Method == UnsubscribeMethod.MailTo)
+            return Ok(new { method = "mailto", target = item.UnsubscribeTarget });
+
+        var result = await _unsub.ProcessQueueAsync(UserId, new UnsubscribeRequestDto(new[] { item.Id }, Confirmed: true), ct);
+        return result.Succeeded ? Ok(new { method = "auto", succeeded = result.Value!.SucceededCount > 0 })
+            : BadRequest(new { error = result.Error });
+    }
+
     private async Task<IActionResult> Act(Guid id, CleanupActionType action, CancellationToken ct)
     {
         var req = new CleanupRequestDto(action, new[] { id }, null, null, Confirmed: true);