feat: cookie consent extension support (ARCHIVR_COOKIE_EXT)

Mirrors the uBlock Origin Lite integration exactly:

Backend:
- singlefile.rs: resolve_cookie_ext_config() reads ARCHIVR_COOKIE_CONSENT
  (default true) + ARCHIVR_COOKIE_EXT path; extension paths comma-joined
  into --load-extension / --disable-extensions-except so uBlock and cookie
  ext can coexist; SaveResult.cookie_ext_skipped tracks miss
- database.rs: cookie_ext_enabled column on instance_settings (DEFAULT 1);
  idempotent ALTER TABLE migration; get/update wired through
- capture.rs: CaptureConfig.cookie_ext_enabled: Option<bool>; threaded to
  singlefile::save(); cookie_ext_skipped surfaced in CaptureResult
- routes.rs: CaptureBody + UpdateInstanceSettingsBody get cookie_ext_enabled;
  capture handler resolves effective value (body overrides global); notes_json
  only includes skipped fields that are true; GET instance-settings includes
  cookie_ext_available from env path check

Frontend:
- api.js: submitCapture forwards cookie_ext_enabled
- SettingsView.jsx: 'I Still Don't Care About Cookies' card in Extensions
  tab; always-active toggle (user can disable even when ext not installed);
  amber 'Not configured' hint + ARCHIVR_COOKIE_EXT guidance when unavailable
- CaptureDialog.jsx: 'Block cookie banners' toggle in Advanced options;
  always shown with amber hint when ext not configured; defaults from
  global setting

Operator setup: download + unzip the extension from GitHub releases, set
ARCHIVR_COOKIE_EXT=/path/to/unpacked/ext. No Node daemon needed.

crates/archivr-core/src/database.rs

@@ -140,6 +140,8 @@ pub struct InstanceSettings {
     /// Global default for ad-blocking via uBlock Origin Lite during WebPage captures.
     /// Per-capture requests can override this.
     pub ublock_enabled: bool,
+    /// Global default for cookie-consent banner dismissal via extension during WebPage captures.
+    pub cookie_ext_enabled: bool,
 }
 
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
@@ -198,7 +200,8 @@ pub fn initialize_schema(conn: &Connection) -> Result<()> {
             id INTEGER PRIMARY KEY CHECK (id = 1),
             public_index_enabled INTEGER NOT NULL DEFAULT 0 CHECK (public_index_enabled IN (0, 1)),
             public_entry_content_enabled INTEGER NOT NULL DEFAULT 0 CHECK (public_entry_content_enabled IN (0, 1)),
-            public_archive_submission_enabled INTEGER NOT NULL DEFAULT 0 CHECK (public_archive_submission_enabled IN (0, 1))
+            public_archive_submission_enabled INTEGER NOT NULL DEFAULT 0 CHECK (public_archive_submission_enabled IN (0, 1)),
+            cookie_ext_enabled INTEGER NOT NULL DEFAULT 1 CHECK (cookie_ext_enabled IN (0, 1))
         );
 
         INSERT OR IGNORE INTO instance_settings (
@@ -464,7 +467,8 @@ pub fn initialize_auth_schema(conn: &Connection) -> Result<()> {
             public_entry_content_enabled       INTEGER NOT NULL DEFAULT 0 CHECK (public_entry_content_enabled IN (0, 1)),
             public_archive_submission_enabled  INTEGER NOT NULL DEFAULT 0 CHECK (public_archive_submission_enabled IN (0, 1)),
             default_entry_visibility           INTEGER NOT NULL DEFAULT 2,
-            ublock_enabled                     INTEGER NOT NULL DEFAULT 1 CHECK (ublock_enabled IN (0, 1))
+            ublock_enabled                     INTEGER NOT NULL DEFAULT 1 CHECK (ublock_enabled IN (0, 1)),
+            cookie_ext_enabled                 INTEGER NOT NULL DEFAULT 1 CHECK (cookie_ext_enabled IN (0, 1))
         );
 
         INSERT OR IGNORE INTO instance_settings
@@ -509,6 +513,11 @@ pub fn initialize_auth_schema(conn: &Connection) -> Result<()> {
         "ALTER TABLE instance_settings ADD COLUMN ublock_enabled INTEGER NOT NULL DEFAULT 1",
         [],
     );
+    // Add cookie_ext_enabled column to instance_settings if not present (idempotent migration)
+    let _ = conn.execute(
+        "ALTER TABLE instance_settings ADD COLUMN cookie_ext_enabled INTEGER NOT NULL DEFAULT 1",
+        [],
+    );
 
     Ok(())
 }
@@ -735,7 +744,8 @@ pub fn get_instance_settings(conn: &Connection) -> Result<InstanceSettings> {
     conn.query_row(
         "SELECT public_index_enabled, public_entry_content_enabled,
                 public_archive_submission_enabled, default_entry_visibility,
-                COALESCE(ublock_enabled, 1)
+                COALESCE(ublock_enabled, 1),
+                COALESCE(cookie_ext_enabled, 1)
          FROM instance_settings WHERE id = 1",
         [],
         |row| {
@@ -745,6 +755,7 @@ pub fn get_instance_settings(conn: &Connection) -> Result<InstanceSettings> {
                 open_registration_enabled: row.get::<_, i64>(2)? != 0,
                 default_entry_visibility: row.get::<_, i64>(3)? as u32,
                 ublock_enabled: row.get::<_, i64>(4)? != 0,
+                cookie_ext_enabled: row.get::<_, i64>(5)? != 0,
             })
         },
     )
@@ -758,7 +769,8 @@ pub fn update_instance_settings(conn: &Connection, settings: &InstanceSettings)
              public_entry_content_enabled = ?2,
              public_archive_submission_enabled = ?3,
              default_entry_visibility = ?4,
-             ublock_enabled = ?5
+             ublock_enabled = ?5,
+             cookie_ext_enabled = ?6
          WHERE id = 1",
         params![
             settings.public_index_enabled as i64,
@@ -766,6 +778,7 @@ pub fn update_instance_settings(conn: &Connection, settings: &InstanceSettings)
             settings.open_registration_enabled as i64,
             settings.default_entry_visibility as i64,
             settings.ublock_enabled as i64,
+            settings.cookie_ext_enabled as i64,
         ],
     )?;
     Ok(())