docs: api comments say what the endpoints do, not how they came to be (#6277)

Rewrites the internal/api comment blocks to rule 32: task, milestone and
rule ids gone, the stories behind them restated as the constraint they
left, stale references corrected (the stream secret is wired from config,
the timezone handler already refreshes the scheduler, the Android app is
the native client, the design docs cited are not in the repo). Also
rewraps comment lines over 80 columns left by the earlier batches.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/me_sessions_test.go

@@ -49,8 +49,8 @@ func withURLParam(r *http.Request, key, value string) *http.Request {
 	return r.WithContext(context.WithValue(r.Context(), chi.RouteCtxKey, rctx))
 }
 
-// The rule #47 assertion. A delete keyed only on session id would let any
-// household member revoke any other member's session by id — this pins that
+// Household data stays per-user: a delete keyed only on session id would let
+// any household member revoke any other member's session by id — this pins that
 // the user scope is actually in the WHERE clause and not just intended.
 func TestRevokeMySession_CannotRevokeAnotherUsersSession(t *testing.T) {
 	h, pool := testHandlers(t)