Cut what the audit found: dead columns, one-time upgrades, three deps

Works through TODO.md from the 2026-09-12 over-engineering audit. Drops the
entries.read/flagged/position columns (migrate() removes them from older
databases), migrate_opml_children, the legacy interval_mins key, the
contrib/ systemd units, test-only Db wrappers, a duplicate token generator,
redundant logbuf visitors, unused page state and CSS, and the infer, dirs
and tokio-stream dependencies. The icon is served once as /icon.png instead
of inlined four times, taking about 94 KB off the two pages.

The adoption's subscription half was not dead: it gives a fresh install's
first admin the config's feeds. It stays as adopt_catalogue, now tested.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TAC7sLVqfKmY6rsTLXzNgk

Cargo.toml

@@ -11,9 +11,7 @@ atom_syndication = "0.12.10"
 axum = "0.8.9"
 chrono = { version = "0.4.45", default-features = false, features = ["std", "clock"] }
 clap = { version = "4.6.6", features = ["derive"] }
-dirs = "7.0.0"
 futures-util = { version = "0.3.34", default-features = false, features = ["std"] }
-infer = "0.22.0"
 librqbit = { version = "9.0.1", default-features = false, features = ["rust-tls", "http-api-client"] }
 opml = "1.1.6"
 percent-encoding = "2.3.2"
@@ -24,7 +22,6 @@ rusqlite = { version = "0.40.2", features = ["bundled"] }
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.151"
 tokio = { version = "1.53.1", features = ["rt-multi-thread", "macros", "fs", "io-util", "net", "sync", "time", "signal"] }
-tokio-stream = { version = "0.1.19", features = ["sync"] }
 toml = "1.1.5"
 tower = { version = "0.5.3", features = ["util"] }
 tower-http = { version = "0.7.1", features = ["fs"] }