feat(publish): releases in git (public tier, stage 2)

A person with an identity and a public profile publishes a studyset with
everything inside it as its next release (ADR 0005, rule 3): the server
reads their synced rows and writes them through the git command as a
commit on main and the annotated tag vN, in a bare repository of the
studyset's own, named by a random public id made at the first publish.

A release is a directory per studyset with a file per card, note, path,
step and PDF (its id, position, tag names and payload as synced, keys
sorted and indented) and the files the content names, without what is
only the author's (a card's report, a PDF's deadline). Publishing is
refused without a licence allowing passing it on in every studyset ("no
derivatives" allowed), with revisions to settle, with files not uploaded
yet, when nothing changed, or for a name that won't do; the name is
fixed from the first release, as is the person's handle.

In the app, Share in a studyset's action row opens the Publish sheet;
publishing syncs first, and settles by itself the revisions that merge
cleanly, listing only real conflicts. The server's image gets git, the
repositories a volume of their own, and the hourly backup a git bundle of
each.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_en.arb

@@ -1582,5 +1582,51 @@
   "cardBrowserResetMessage": "They count as new again. Their reviews stay in your history and streaks.",
   "cardBrowserResetConfirm": "Reset",
   "cardBrowserReset": "{count, plural, =1{1 flashcard starts afresh} other{{count} flashcards start afresh}}",
-  "@cardBrowserReset": {"placeholders": {"count": {"type": "int"}}}
+  "@cardBrowserReset": {"placeholders": {"count": {"type": "int"}}},
+  "studysetShare": "Share",
+  "studysetSharePrivate": "Share: private",
+  "studysetSharePublished": "Share: published",
+  "publishTitle": "Publish",
+  "publishPrivate": "Private · only you can see it",
+  "publishPublished": "Published · v{version} · {date}",
+  "@publishPublished": {"placeholders": {"version": {"type": "int"}, "date": {"type": "String"}}},
+  "publishIntro": "A release is this studyset with everything inside it, as it is now. Others can find it, learn from it and copy it. Each release stays as it was; later changes go into the next one.",
+  "publishAnonymous": "Sign in with GitHub to have a public profile and publish.",
+  "publishName": "Name",
+  "publishNameHint": "japanese",
+  "publishLocation": "Found at {location}",
+  "@publishLocation": {"placeholders": {"location": {"type": "String"}}},
+  "publishNameFixed": "Fixed since you first published: others refer to it.",
+  "publishLicence": "Licence",
+  "publishLicenceNone": "None",
+  "publishLicenceOpen": "Allows publishing.",
+  "publishLicenceNoDerivatives": "Allows publishing as it is: learners keep their changes to themselves.",
+  "publishLicenceClosed": "Doesn't allow passing it on. Choose another under Edit.",
+  "publishLicenceNotOpen": "These studysets' licences don't allow passing them on: {titles}",
+  "@publishLicenceNotOpen": {"placeholders": {"titles": {"type": "String"}}},
+  "publishNotes": "What changed",
+  "publishNotesHint": "New in this release…",
+  "publishReleases": "Releases",
+  "publishRelease": "v{version} · {date}",
+  "@publishRelease": {"placeholders": {"version": {"type": "int"}, "date": {"type": "String"}}},
+  "publishButton": "Publish v{version}",
+  "@publishButton": {"placeholders": {"version": {"type": "int"}}},
+  "publishNoProfile": "A release names you by your public profile. Make one first.",
+  "publishMakeProfile": "Make a public profile",
+  "publishConflicts": "These were changed differently on two devices. Settle them first:",
+  "publishConflictsElsewhere": "Some cards, notes or steps were changed differently on two devices. Sync, then try again.",
+  "publishUntitled": "Untitled",
+  "publishFilesMissing": "Some files haven't reached your instance yet. Try again in a moment.",
+  "publishNothingChanged": "Nothing has changed since the last release.",
+  "publishBusy": "This studyset is being published already. Try again in a moment.",
+  "publishSlugInvalid": "Lower-case letters, digits and hyphens, starting with a letter or digit.",
+  "publishSlugTaken": "Another of your studysets has this name.",
+  "publishNotesTooLong": "At most 5,000 characters.",
+  "publishDone": "Published v{version}.",
+  "@publishDone": {"placeholders": {"version": {"type": "int"}}},
+  "publishFailed": "Couldn't reach your instance. Nothing was published.",
+  "publishUnreachable": "Publishing can't be reached right now.",
+  "publishRetry": "Retry",
+  "publishCopyLocation": "Copy address",
+  "publishLocationCopied": "Address copied."
 }