Gate pedigree behind a dog id set in settings

The pedigree view is now opt-in and tied to your own dog rather than an
always-present free-text search. Add the dog's SKK chip or registration
number in Settings (it rides the synced profile alongside name and
birthday); the 🌳 button stays hidden until one is set, then opens the
page and loads that dog's ancestry directly.

Make repeat opens cheap: memoise the id->hundid resolution server-side so
a cached tree is served without contacting SKK at all, and mirror the
finished tree in localStorage so the page paints instantly and shows the
last-known tree offline.

Adds config.pedigree_id (with an in-place migration for existing DBs).

src/changelog.json

@@ -1,5 +1,5 @@
 [
-  { "date": "2026-07-26", "text": "New 🌳 Pedigree page: look up any dog in SKK Hunddata by chip or registration number and explore its ancestry as a tree — the first generations show at once, then the line fills in further back as it's traced" },
+  { "date": "2026-07-26", "text": "New 🌳 Pedigree page: add your dog's SKK chip or registration number in Settings to unlock it, then explore its ancestry as a tree — the first generations show at once and the line fills in further back as it's traced from SKK Hunddata. It's cached, so it reopens instantly and works offline" },
   { "date": "2026-07-24", "text": "The age counter reads \"16 weeks (3 months and 3 weeks) old\" so weeks and months line up; past 4 months it drops the weeks and shows just months (e.g. \"5 months and 2 weeks old\")" },
   { "date": "2026-07-17", "text": "The Sleep trend chart follows the selected day — pick a past day to see its full curve against the day before and the average leading up to it" },
   { "date": "2026-07-15", "text": "The Sleep trend y-axis is stretched above 10h, giving the hours around the sleep goal most of the chart" },