Initial commit: The Daily EPUB full implementation

Full implementation of a personalized daily newspaper delivered as an
EPUB.

Articles are pulled from a local self-hosted Miniflux instance, enriched
with comments, summarized and filtered by DeepSeek AI, and then
assembled into two EPUB editions: standard and optimized for the Xteink
X4 e-ink reader. Both are served by the local self-hosted BookOrbit OPDS
server in a separate library. Then the X4 edition is futher converted to
XTC format and served over a separate OPDS server hosted by the Rust
binary. Runs are tracked in a local SQLite database so runs are
idempotent per date.

Full documentation of the plan is in docs/plans and setup and install
instructions are in the README.md file.

tests/fixtures/reddit_comments.json

@@ -0,0 +1,76 @@
+[
+  {
+    "kind": "Listing",
+    "data": {
+      "children": [
+        {
+          "kind": "t3",
+          "data": {
+            "title": "A Story About Databases",
+            "permalink": "/r/rust/comments/abc/title/",
+            "score": 512,
+            "num_comments": 87
+          }
+        }
+      ]
+    }
+  },
+  {
+    "kind": "Listing",
+    "data": {
+      "children": [
+        {
+          "kind": "t1",
+          "data": {
+            "author": "ferris",
+            "score": 55,
+            "body": "The borrow checker earns its keep here.",
+            "body_html": "<div class=\"md\"><p>The borrow checker earns its keep here.</p></div>",
+            "replies": {
+              "kind": "Listing",
+              "data": {
+                "children": [
+                  {
+                    "kind": "t1",
+                    "data": {
+                      "author": "crab",
+                      "score": 12,
+                      "body_html": "<div class=\"md\"><p>Only if you never fight it.</p></div>",
+                      "replies": ""
+                    }
+                  },
+                  {
+                    "kind": "more",
+                    "data": { "count": 14, "children": ["x1", "x2"] }
+                  }
+                ]
+              }
+            }
+          }
+        },
+        {
+          "kind": "t1",
+          "data": {
+            "author": "[deleted]",
+            "score": 1,
+            "body_html": "<div class=\"md\"><p>[removed]</p></div>",
+            "replies": ""
+          }
+        },
+        {
+          "kind": "t1",
+          "data": {
+            "author": "rustacean",
+            "score": 31,
+            "body_html": "<div class=\"md\"><p>The section on "unsafe" is the best part.</p></div>",
+            "replies": ""
+          }
+        },
+        {
+          "kind": "more",
+          "data": { "count": 40, "children": ["y1"] }
+        }
+      ]
+    }
+  }
+]