Replace named Ratatui colors with RGB values

Update docs, increase test count to 107, adjust flake.lock, and modify
rendering logic to use explicit Color::Rgb throughout the codebase.

flake.lock

@@ -8,11 +8,11 @@
         "rust-analyzer-src": "rust-analyzer-src"
       },
       "locked": {
-        "lastModified": 1792494797,
-        "narHash": "sha256-W0hLL8YLjWT/QlHcnNbON3EeDostg+GD9fw6rv4jbyY=",
+        "lastModified": 1792926139,
+        "narHash": "sha256-uLMpwLKdV5U1966bkbe5DzC+5Gp8O6g+wjydKmih7zQ=",
         "owner": "nix-community",
         "repo": "fenix",
-        "rev": "e77f56ee0521b21e5a987dd3e88b6bb367d777a7",
+        "rev": "44ec3e059cf1631403a0faca34106be5fdb17631",
         "type": "github"
       },
       "original": {
@@ -46,11 +46,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1792502884,
-        "narHash": "sha256-IoNisKcGbUjdd45qCqywGMCYmZ5EnkxezvLII0FWwNA=",
+        "lastModified": 1792773339,
+        "narHash": "sha256-rZLrzrC6i+jnTAlvPZHogKDulY7WWDEv9hJeHieO7Zw=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "02c087f3fe673c9e317f206a627cb6b910336dbe",
+        "rev": "3ec636362e1816bc2f0888fa0fa2c69f1bc9e504",
         "type": "github"
       },
       "original": {
@@ -70,11 +70,11 @@
     "rust-analyzer-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1792431056,
-        "narHash": "sha256-FiKlJK+NoB9J9+xIQPfJaRfK42msh55Pt6FsJ++NcxY=",
+        "lastModified": 1792691653,
+        "narHash": "sha256-3/DMV3Lpmthk6OV2b7bJSJ5Okouyvl755YZENyLwllo=",
         "owner": "rust-lang",
         "repo": "rust-analyzer",
-        "rev": "7afa765037d97a62b53c59907e9f503409f2a673",
+        "rev": "0c4d74686b21f2b3bd8872b6d3cf36ad2e740d49",
         "type": "github"
       },
       "original": {