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/lobsters_story.json

@@ -0,0 +1,41 @@
+{
+  "short_id": "abcdef",
+  "title": "A Story About Databases",
+  "url": "https://example.com/databases",
+  "score": 48,
+  "comment_count": 4,
+  "comments": [
+    {
+      "short_id": "c1",
+      "comment": "<p>Nice writeup of the write path.</p>",
+      "score": 20,
+      "indent_level": 1,
+      "parent_comment": null,
+      "commenting_user": "pushcx"
+    },
+    {
+      "short_id": "c2",
+      "comment": "<p>Do you have numbers for NVMe?</p>",
+      "score": 9,
+      "indent_level": 2,
+      "parent_comment": "c1",
+      "commenting_user": { "username": "second" }
+    },
+    {
+      "short_id": "c3",
+      "comment": "<p>Yes, in the appendix.</p>",
+      "score": 4,
+      "indent_level": 3,
+      "parent_comment": "c2",
+      "commenting_user": "third"
+    },
+    {
+      "short_id": "c4",
+      "comment": "<p>Unrelated: the site's typography is lovely.</p>",
+      "score": 3,
+      "indent_level": 1,
+      "parent_comment": null,
+      "commenting_user": "other"
+    }
+  ]
+}