chore: rebrand Subfeed -> Siftlode

Rename all user-facing references (UI wordmark Sift+lode, titles, app name,
legal pages, onboarding wizard, emails, README/docs) and infra paths
(/srv/subfeed -> /srv/siftlode, image tag, deploy script, backup filenames).

Internal identifiers kept on purpose: Postgres user/db "subfeed", logger
namespace, localStorage keys, and the subfeed_pgdata volume (renaming would
orphan the migrated production data).

frontend/src/components/legal/LegalLayout.tsx

@@ -24,7 +24,7 @@ export default function LegalLayout({
     <div className="min-h-screen bg-bg text-fg">
       <div className="mx-auto w-[min(92vw,720px)] py-12">
         <a href="/" className="inline-block text-2xl font-bold tracking-tight mb-8">
-          Sub<span className="text-accent">feed</span>
+          Sift<span className="text-accent">lode</span>
         </a>
         <div className="glass rounded-2xl p-8">
           <h1 className="text-2xl font-semibold">{title}</h1>

frontend/src/components/legal/PrivacyPolicy.tsx

@@ -4,14 +4,14 @@ export default function PrivacyPolicy() {
   return (
     <LegalLayout title="Privacy Policy">
       <p>
-        Subfeed is a personal, non-commercial project operated by an individual in Hungary
+        Siftlode is a personal, non-commercial project operated by an individual in Hungary
         ("we", "us"). It lets you view and organize your own YouTube subscriptions as a
-        filterable feed. This policy explains what data Subfeed accesses, how it is used, and
-        the choices you have. By using Subfeed you agree to this policy.
+        filterable feed. This policy explains what data Siftlode accesses, how it is used, and
+        the choices you have. By using Siftlode you agree to this policy.
       </p>
 
       <H2>What we access</H2>
-      <p>Subfeed only accesses data you explicitly authorize, in two separate steps:</p>
+      <p>Siftlode only accesses data you explicitly authorize, in two separate steps:</p>
       <ul className="list-disc pl-5 space-y-1">
         <li>
           <span className="text-fg font-medium">Sign-in (always):</span> your basic Google
@@ -31,13 +31,13 @@ export default function PrivacyPolicy() {
         </li>
       </ul>
       <p>
-        You can use Subfeed with sign-in alone, and grant or decline each YouTube permission
+        You can use Siftlode with sign-in alone, and grant or decline each YouTube permission
         independently.
       </p>
 
       <H2>How we use it</H2>
       <p>
-        Your data is used exclusively to provide Subfeed's features to you: building and
+        Your data is used exclusively to provide Siftlode's features to you: building and
         displaying your personalized subscription feed, and carrying out actions (such as
         unsubscribing) that you initiate. We do not use it for advertising, profiling, or any
         purpose unrelated to the app.
@@ -45,7 +45,7 @@ export default function PrivacyPolicy() {
 
       <H2>Limited Use disclosure</H2>
       <p>
-        Subfeed's use and transfer of information received from Google APIs to any other app
+        Siftlode's use and transfer of information received from Google APIs to any other app
         will adhere to the{" "}
         <LegalLink href="https://developers.google.com/terms/api-services-user-data-policy">
           Google API Services User Data Policy
@@ -65,7 +65,7 @@ export default function PrivacyPolicy() {
 
       <H2>Retention &amp; deletion</H2>
       <p>
-        We keep your data while your account is active. You can revoke Subfeed's access to your
+        We keep your data while your account is active. You can revoke Siftlode's access to your
         Google data at any time at{" "}
         <LegalLink href="https://myaccount.google.com/permissions">
           myaccount.google.com/permissions
@@ -80,13 +80,13 @@ export default function PrivacyPolicy() {
 
       <H2>Cookies</H2>
       <p>
-        Subfeed sets a single, signed session cookie to keep you logged in. It is not used for
+        Siftlode sets a single, signed session cookie to keep you logged in. It is not used for
         tracking or advertising, and there are no third-party analytics cookies.
       </p>
 
       <H2>YouTube &amp; Google</H2>
       <p>
-        Subfeed uses YouTube API Services. By using Subfeed you also agree to the{" "}
+        Siftlode uses YouTube API Services. By using Siftlode you also agree to the{" "}
         <LegalLink href="https://www.youtube.com/t/terms">YouTube Terms of Service</LegalLink>,
         and your use of Google data is subject to the{" "}
         <LegalLink href="https://policies.google.com/privacy">Google Privacy Policy</LegalLink>.

frontend/src/components/legal/Terms.tsx

@@ -4,21 +4,21 @@ export default function Terms() {
   return (
     <LegalLayout title="Terms of Service">
       <p>
-        Subfeed is a personal, non-commercial project operated by an individual in Hungary. It
+        Siftlode is a personal, non-commercial project operated by an individual in Hungary. It
         provides a filterable view of your own YouTube subscriptions. By accessing or using
-        Subfeed, you agree to these Terms. If you do not agree, do not use the service.
+        Siftlode, you agree to these Terms. If you do not agree, do not use the service.
       </p>
 
       <H2>The service</H2>
       <p>
-        Subfeed is offered on an invite-only basis, free of charge, and "as is", without
+        Siftlode is offered on an invite-only basis, free of charge, and "as is", without
         warranties of any kind. It is a hobby project: features may change, and the service may
         be slowed, interrupted, or discontinued at any time without notice.
       </p>
 
       <H2>Your account &amp; acceptable use</H2>
       <p>
-        You sign in with your Google account and may only access Subfeed with an email that has
+        You sign in with your Google account and may only access Siftlode with an email that has
         been invited. You agree to use the service lawfully, not to abuse, disrupt, probe, or
         overload it, and not to attempt to access other users' data. We may suspend or revoke
         access at our discretion, for example in case of misuse.
@@ -26,7 +26,7 @@ export default function Terms() {
 
       <H2>Third-party services</H2>
       <p>
-        Subfeed uses YouTube API Services. By using Subfeed you agree to be bound by the{" "}
+        Siftlode uses YouTube API Services. By using Siftlode you agree to be bound by the{" "}
         <LegalLink href="https://www.youtube.com/t/terms">YouTube Terms of Service</LegalLink>.
         Your data is handled as described in our{" "}
         <a href="/privacy" className="text-accent hover:underline">Privacy Policy</a> and, for
@@ -38,7 +38,7 @@ export default function Terms() {
       <p>
         To the maximum extent permitted by law, the service is provided without warranty, and
         the operator is not liable for any indirect, incidental, or consequential damages, or
-        for any loss of data, arising from your use of Subfeed. Your sole remedy if you are
+        for any loss of data, arising from your use of Siftlode. Your sole remedy if you are
         dissatisfied is to stop using the service and revoke its access to your account.
       </p>