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.lock

@@ -436,17 +436,6 @@ dependencies = [
  "shlex",
 ]
 
-[[package]]
-name = "cfb"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a347dcabdae9c31b0825fd6a8bed285ec9c2acb89c47827126d52fa4f59cece3"
-dependencies = [
- "fnv",
- "uuid",
- "web-time",
-]
-
 [[package]]
 name = "cfg-if"
 version = "1.0.4"
@@ -867,15 +856,6 @@ dependencies = [
  "dirs-sys",
 ]
 
-[[package]]
-name = "dirs"
-version = "7.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d57d423b3c82e89b9a24ca3091fee61f456a26edbd28d26c65906f4bc1dcd8f"
-dependencies = [
- "dirs-sys",
-]
-
 [[package]]
 name = "dirs-sys"
 version = "0.5.0"
@@ -1608,15 +1588,6 @@ dependencies = [
  "serde_core",
 ]
 
-[[package]]
-name = "infer"
-version = "0.22.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f4200d433cbd5178df7797c9c2e75b348b728e39631cf14520d1e2fc424201f4"
-dependencies = [
- "cfb",
-]
-
 [[package]]
 name = "intervaltree"
 version = "0.2.7"
@@ -1643,9 +1614,7 @@ dependencies = [
  "axum",
  "chrono",
  "clap",
- "dirs",
  "futures-util",
- "infer",
  "librqbit",
  "opml",
  "percent-encoding",
@@ -1656,7 +1625,6 @@ dependencies = [
  "serde",
  "serde_json",
  "tokio",
- "tokio-stream",
  "toml",
  "tower",
  "tower-http 0.7.1",