feat: add sender blocklist with priority matching and quick-add dropdown

- Add `blocked_senders` field to FeedConfig (alongside existing `allowed_senders`)
- Refactor sender matching to priority-based logic: exact block > exact allow > domain block > domain allow, enabling exceptions (e.g. allow toto@gmail.com despite blocking gmail.com)
- Add `POST /admin/feeds/:feedId/sender-filter` endpoint for quick allow/block from email detail view; returns 409 on conflict with opposite list
- Add ⋮ dropdown on From field in email detail with 4 options (allow/block sender/domain), inline success/error feedback
- Add blocked_senders textarea to create/edit feed forms
- 209 tests passing

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/lib/email-processor.test.ts

@@ -86,6 +86,69 @@ describe("processEmail", () => {
     expect(res.status).toBe(200);
   });
 
+  it("returns 403 when sender is in blocklist by exact address", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({ blocked_senders: ["sender@example.com"] }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(403);
+  });
+
+  it("returns 403 when sender is in blocklist by domain", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({ blocked_senders: ["example.com"] }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(403);
+  });
+
+  it("returns 200 when sender is not in blocklist", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({ blocked_senders: ["other@example.com"] }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(200);
+  });
+
+  it("exact block takes precedence over domain allow", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({
+        allowed_senders: ["example.com"],
+        blocked_senders: ["sender@example.com"],
+      }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(403);
+  });
+
+  it("exact allow overrides domain block (exception use case)", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({
+        allowed_senders: ["sender@example.com"],
+        blocked_senders: ["example.com"],
+      }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(200);
+  });
+
+  it("exact block takes precedence over exact allow", async () => {
+    await env.EMAIL_STORAGE.put(
+      `feed:${VALID_FEED_ID}:config`,
+      JSON.stringify({
+        allowed_senders: ["sender@example.com"],
+        blocked_senders: ["sender@example.com"],
+      }),
+    );
+    const res = await processEmail(makeInput(), env as any);
+    expect(res.status).toBe(403);
+  });
+
   it("stores email data and updates metadata in KV", async () => {
     await env.EMAIL_STORAGE.put(
       `feed:${VALID_FEED_ID}:config`,