feat(analysis): add ocrs OCR backend and OCR-driven page text search

Adds an in-process ocrs OCR backend as the active analysis engine
(vision left dormant), enables OCR text search on the page-tag
aggregation endpoints, and reshapes the admin analysis/settings UI to
present the OCR-only surface. Bumps version 0.89.0 -> 0.90.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.89.0"
+version = "0.90.0"
 edition = "2021"
 default-run = "mangalord"
 
@@ -52,6 +52,8 @@ sysinfo = { version = "0.32", default-features = false, features = ["system", "c
 nix = { version = "0.29", features = ["fs"] }
 scraper = "0.20"
 reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "socks", "cookies", "stream", "json"] }
+ocrs = "0.12"
+rten = "0.24"
 
 [dev-dependencies]
 tempfile = "3"