feat(projekter): en deling siger til, og der er en vej ud af den

Spørgsmålet var, om modtageren ikke burde godkende først. Svaret er nej — men
det, spørgsmålet fik øje på, var rigtigt, og værre end det lød.

Tre ting gjaldt samtidig: man blev tilføjet uden at blive spurgt, man fik ikke
besked, og man kunne ikke gå ud igen. En delt note gav en klokkebesked; et delt
projekt gav ingenting — det stod bare i sidebjælken næste gang, man kiggede,
uden at noget sagde hvornår eller fra hvem. Og handleRemoveMember lå bag
ejer-kravet, så kun ejeren kunne fjerne nogen, også en selv.

Hvert enkelt af de tre er til at leve med. Alle tre sammen gør en deling til
noget, der sker for en.

Ikke et godkendelsestrin: en invitation, der venter på et ja, betyder, at den,
der delte, tror det er gjort, mens arbejdet ligger stille — og noter deles
allerede uden. Det, der manglede, var besked og en udgang.

`project.shared` er ny. Klokkens follow() kunne allerede føre et project_id hen
til projektet, så beskeden bærer sit eget mål og krævede ingen særregel.

Ruten til at fjerne et medlem er flyttet ud af ejer-gruppen, og handleren skiller
nu de to ting ad: ejeren, der fjerner nogen, og den, der selv går. At pege på en
andens medlemskab uden at eje projektet svarer 404 og ikke 403 — "det må du
ikke" bekræfter, at medlemskabet findes. Ejeren kan stadig ikke gå fra sit eget
projekt; det ville være en overdragelse, og den findes ikke endnu.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/notifications.md

@@ -11,6 +11,7 @@ the app's icon.
 | --- | --- |
 | Somebody edited a note shared with you | Repeat edits fold into one line while it is unread |
 | Somebody shared a note with you | Once, when it happens |
+| Somebody shared a project with you | Once, when it happens — the entry opens the project, and its share panel has a *Leave the project* button |
 | Somebody named you in a note with `@` | Instead of "edited a note" — one act, one message |
 | Somebody gave you a task | Only on the change, and only to the person who got it |
 | Somebody commented | |

docs/openapi.yaml

@@ -2379,8 +2379,19 @@ paths:
         "422": { $ref: "#/components/responses/Validation" }
     delete:
       tags: [projects]
-      summary: Remove somebody from a project. Its owner only.
+      summary: Remove somebody from a project — its owner, or yourself.
       description: |
+        Two things through one route: the owner taking somebody off, and anybody
+        taking themselves off. The second is what makes a share something you can
+        undo. You are let into a project without being asked, so a way out that
+        does not go through asking its owner is the other half of that.
+
+        The owner cannot leave their own project. That is a transfer of ownership,
+        not an exit, and there is no transfer yet.
+
+        Pointing at somebody else's membership without owning the project answers
+        404 rather than 403: saying "you may not" confirms the membership exists.
+
         Their tasks are unassigned rather than left pointing at somebody who can
         no longer see the project — which is why changing a role is a PATCH and
         not a remove-and-reinvite.

docs/signing-in.md

@@ -24,6 +24,16 @@ becomes a link that creates their account and their membership at once. With no
 mail server configured the link is shown in the panel instead of being sent, which
 is the correct behaviour on a one-person instance rather than an error.
 
+**You are told, and you can leave.** Being added to a project is not something
+that happens to you quietly: the bell says who shared what, and the entry takes
+you to the project. In the share panel, anybody who is not the owner has a *Leave
+the project* button. That is deliberate rather than an approval step — an
+invitation waiting on a yes means the person who shared thinks it is done while
+the work sits still. What was wrong was the other three-quarters of it: you were
+added without being asked, without being told, and with no way out except asking
+the owner. The owner cannot leave their own project; that is a transfer of
+ownership, and there is no transfer yet.
+
 An invitation that has not been taken up stays listed under the members, greyed,
 with a × to withdraw it. Without that it is invisible — the person has no account,
 so they are neither a member nor somebody you can pick — and the usual next move