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

1 files changed, 26 insertions, 0 deletions

diff --git a/web/templates/settings.html b/web/templates/settings.html
index 8a72287..1156ef5 100644
--- a/web/templates/settings.html
+++ b/web/templates/settings.html
@@ -215,6 +215,32 @@
                 </div>
             </div>
 
+            <!-- Calendar feeds (.ics) -->
+            <div class="mb-8 p-4 rounded-xl border border-white/10 bg-white/5">
+                <h3 class="text-sm font-semibold uppercase tracking-wider text-slate-500 mb-1">Calendar Feeds (.ics)</h3>
+                <p class="text-xs text-white/40 mb-4">
+                    Subscribed calendars fetched directly by doot. Google Calendar is read
+                    through a service account, which cannot see calendars you subscribe to
+                    in your own account &mdash; so published schedules go here instead.
+                </p>
+
+                {{template "ics-feed-list" .}}
+
+                <form class="flex flex-wrap gap-2 mt-4"
+                      hx-post="/settings/ics-feeds"
+                      hx-target="#ics-feed-list"
+                      hx-swap="outerHTML"
+                      hx-on::after-request="if(event.detail.successful) this.reset()">
+                    <input type="text" name="name" placeholder="Name (e.g. Seahawks)" required
+                           class="flex-1 min-w-32 bg-input border border-white/20 rounded-lg px-3 py-2 text-sm text-white placeholder-white/40">
+                    <input type="text" name="url" placeholder="https://... .ics or webcal://..." required
+                           class="flex-[2] min-w-48 bg-input border border-white/20 rounded-lg px-3 py-2 text-sm text-white placeholder-white/40">
+                    <button type="submit" class="bg-white/20 hover:bg-white/30 text-white px-4 py-2 rounded-lg text-sm font-medium transition-colors">
+                        Add Feed
+                    </button>
+                </form>
+            </div>
+
             {{template "sync-log" .SyncLog}}
 
             <div id="sources-container" class="grid gap-8 mt-8">