Add .ics calendar feed support

doot reads Google Calendar through a service account, by calendar ID. That
cannot consume an .ics URL, and it cannot see a calendar subscribed to inside a
personal Google account either, because Google does not allow re-sharing a
subscribed calendar. Published schedules — sports fixtures, school terms, bin
collections — are distributed almost exclusively as .ics, so none of them could
be added at all.

Feeds are now fetched on the normal calendar refresh and merged into
calendar_events alongside Google events, so the timeline, widget and everything
downstream keep seeing one list and needed no changes.

Failure handling is deliberately asymmetric. A Google error is still returned as
an error, unchanged, so an outage there surfaces. A single failing feed is
recorded against that feed and skipped, because one dead URL should not take the
whole calendar down — and last_error is shown in settings, since a feed that has
quietly stopped resolving otherwise looks identical to a team with no games
left.

The parser handles what real feeds actually contain: line unfolding, CRLF and
LF, UTC / TZID / VALUE=DATE times, and escaped text. Two details worth naming:
a TZID time is wall-clock in that zone, and reading it as UTC would put a 1:15pm
Pacific kickoff on the timeline at 1:15pm local — wrong by the offset but
entirely plausible-looking. And non-calendar content is a hard error rather than
zero events, because an HTML error page from a moved feed URL is the common
failure and "no events" reads as success.

RRULE is deliberately unsupported: every schedule feed this targets expands
recurrence itself, one VEVENT per fixture, and a correct expansion is a large
amount of subtle code. A recurring event appears once rather than wrongly.

Settings gains an add/enable/disable/remove UI. webcal:// links are accepted and
rewritten, since that is how feeds are usually advertised.

16 parser tests, 5 store tests. Verified against the real Seattle Seahawks feed:
21 events, all with valid times.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018AwnALZL6bD4VBtATDVv3B

2 files changed, 30 insertions, 1 deletions

diff --git a/migrations/033_ics_feeds.sql b/migrations/033_ics_feeds.sql
new file mode 100644
index 0000000..b7f2d75
--- /dev/null
+++ b/migrations/033_ics_feeds.sql
@@ -0,0 +1,28 @@
+-- Subscribed iCalendar (.ics) feeds.
+--
+-- doot reads Google Calendar with a service account, by calendar ID. That
+-- cannot consume an .ics URL, and it cannot see a calendar subscribed to inside
+-- a personal Google account either, because Google does not allow re-sharing a
+-- subscribed calendar. Published schedules — sports fixtures being the case
+-- that prompted this — are distributed almost exclusively as .ics.
+--
+-- Feeds are fetched on the normal calendar refresh and their events are merged
+-- into calendar_events alongside Google ones, so they appear on the timeline
+-- without the timeline needing to know they came from a different place.
+--
+-- last_error records the most recent failure and is cleared on success, so a
+-- feed that has quietly stopped resolving is visible in settings rather than
+-- just showing no events.
+
+CREATE TABLE IF NOT EXISTS ics_feeds (
+    id              INTEGER PRIMARY KEY AUTOINCREMENT,
+    name            TEXT NOT NULL,
+    url             TEXT NOT NULL UNIQUE,
+    enabled         INTEGER NOT NULL DEFAULT 1,
+    last_fetched_at DATETIME,
+    last_error      TEXT,
+    event_count     INTEGER NOT NULL DEFAULT 0,
+    created_at      DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX IF NOT EXISTS idx_ics_feeds_enabled ON ics_feeds(enabled);
diff --git a/migrations/README.md b/migrations/README.md
index a98efa2..1564b48 100644
--- a/migrations/README.md
+++ b/migrations/README.md
@@ -28,10 +28,11 @@ Migration 007 was reserved during development but never implemented. The gap is
 
 Migrations are applied automatically on application startup via `store.RunMigrations()`. The `schema_migrations` table tracks which migrations have been applied.
 | 032 | `032_import_trello_shopping_items.sql` | One-time import of Trello Shopping-board cards (Hardware Store + unlisted) into user items, ahead of removing Trello as a shopping source |
+| 033 | `033_ics_feeds.sql` | Subscribed iCalendar (.ics) feeds, merged into calendar_events |
 
 ## Creating New Migrations
 
-1. Create file: `migrations/NNN_description.sql` (next number is 033)
+1. Create file: `migrations/NNN_description.sql` (next number is 034)
 2. Write idempotent SQL (use `IF NOT EXISTS` where possible)
 3. Test locally: `go run cmd/dashboard/main.go`
 4. Verify: Check `schema_migrations` table for new entry